What are the Best Pool Filters for Inground Pools? Welcome to our indepth buying guide where we review and discuss several of the best pool filters for your pool. It can be confusing making sense of all the technical jargon and then determining how one model is different than another, which is why we put together this comprehensive article — to help you determine which pool filter is right for you.
Intro | Best Pool Filters for Inground Pools
In this best pool filters buying guide we will discuss three pool filter types. Trusty sand filters and their competitors, cartridge filters, and diatomaceous earth filters. Which one is the best pool filter for inground pools? I will leave it to you to decide. I’ll discuss each type and also review some from each group. All along, I’ll point out what you need to know to select the best possible filter for your inground pool.
Types of pool filters
Three types of filters are commercially available, the sand filter, pleated cartridges, and D.E. filters that have grids coated with diatomaceous earth powder. But which type of pool filter is the best for inground pools?
Sand is a good filter medium, and it’s been around for many years. When dirt builds up in a sand filter, the pressure inside the filter rises. When this happens, the filter must be backwashed. Which means the water flow direction is reversed to wash out the contaminants. The backwash water is dirty and contains chemicals, so it’s wasted.
The filter sand should be replaced every 7 to 10 years, and normally it’s the only times you open the tank. Sand replacements that are promised to perform even better are available, and it’s something worth considering if you wish to improve your current sand filter. We will discuss all the filter maintenance issues in detail after reviewing the best pool filters for inground pools. For now, you should keep in mind that sand was long considered the best pool filter.
Diatomaceous Earth (DE) | Hayward DE4820 ProGrid D.E.
Filter Cartridges differ from sand filters in that they use pleated polyester filter cartridges instead of sand to filter the dirt. This type of filter is not backwashed, the filters must be removed and hosed clean when the filter tank pressure rises. This type of filter wastes less water than the other filter types, but it requires that you open the filter tank to remove and wash the filters. Filter cartridges do as good a job as the sand filter types. Depending on the amount of dirt that’s filtered, the cartridges should be replaced every 2 to 5 years.
D.E. filters are the most efficient at filtering the water and, therefore, some consider them to be the best pool filters for inground pools. With a D.E. filter, water is pumped through grids inside the tank. The grids provide a large filter area that’s coated with diatomaceous earth (D.E.) powder as the filter media. The D.E. filter is also backwashed to clean it when the water pressure reaches a high point. During backwashing, the D.E. powder is washed away with the dirt, so fresh D.E. powder is added to the pump basket to recoat the grids. Damaged D.E. Grids can be replaced individually, but this won’t be too often – a grid set should last 7-10 years.
Choosing a filter system
In selecting a filter for your pool, there is a lot to consider. So before we review some of the best pool filters for in-ground pools, let’s quickly discuss some of the most critical issues. After the reviews, we’ll have a more in-depth discussion of each filter type. We’ll also cover maintenance issues and algae control.
Does filter size matter?
Filter size does matter. This is one of those times when spending a little more makes a lot of sense. Buy a filter that’s larger than you think you need, as big as you can afford. A larger filter has a bigger filter area that makes it more efficient. It filters better and traps more dirt in a shorter amount of time, so you save on pump running costs. It’s also more effective for a longer period before it needs a clean out, so it saves money through reduced chemical usage and less wastewater. It also saves time and effort, requiring less service and maintenance. When things go wrong, the larger filter will restore water clarity much faster than a smaller pool filter.
Sand filter sizing
The best size sand pool filter for an inground pool over 20,000 gallons is one with at least a 30-inch diameter tank. It offers 4.9 square feet of filter surface area. For smaller pools, you may go one size down. But never go smaller than a 24 to 27-inch diameter tank for an inground pool.
Sizing D.E. filters
One tends to think that D.E. filters may be smaller because of their superior filtration, and some sales staff will recommend a 24 or 36 square foot D.E. filter. The same “bigger-is-better” rule applies here, do not use a filter of less than 46 to 48 square feet. For a pool over 25,000 gallons, go with the 60 to 72 square foot filter.
Sizing Cartridge filters
The minimum size cartridge filters for inground pools should be based on 100 square feet of filter surface area per 10,000 gallons of pool water. Most experts recommend 400 square foot models for inground pools above 25,000 gallons. Cartridge filters offer excellent filtration and, if correctly sized, the period between filter cleaning can be longer than the other filters systems. Compared to sand filters, you’ll experience greater water savings. Cartridge filters do not require backwashing, the filters are removed from the tank and washed with a hose.
Sand Filter : 24″ / 62 GPM — Hayward S244T ProSeries Sand Filter
Fiberglass reinforced — is it worth it?
Fiberglass reinforcing is worth it when it conforms to the BS4994 standards because it’s corrosion resistant and incredibly strong, resisting tensile forces. Chlor-alkali manufacturers usually use vessels designed to BS4994 specifications because of its resistance to the substance. Long-term exposure to ultraviolet light (sunlight) makes the surface of Fiberglass brittle due to chemical changes and it may be of concern to some. But, by the addition of surface gel coats and sealants, the Fiberglass construct can be completely protected against UV exposure. It’s standard practice to use this coating, so the best pool filters for inground pools are always well protected.
If you give your Fiberglass reinforced pool filter the same considerate care, as you do for all your pool equipment, it will provide you with a lifetime of excellent service.
Reviews | Best Pool Filters for Inground Pools
For all types of pool filter the maximum recommended working pressure for all models is 50 psi. After the reviews I will discuss why this is important. The general rule here is that if your pump delivers more pressure than that you will have problems.
Best Pool Filters using pool filter cartridges as a filter media —
Filter cartridge pool filters use the same technology that keeps your engine free of airborne debris. It’s extremely effective and it will ensure that your pool water will be crystal clear and sparkling. We’re going to review two Hayward pool filters : StarClear Plus and SwimClear. Both split in the middle to provide access to the cartridges and the two halves are locked together with a band around the middle. Also in this review is one Pentair Clean & Clear range that split in the middle but use a single knob at the top to lock the two halves together.
Hayward StarClear Plus Series
Reusable polyester filter cartridge. Best Pool Filters for Inground Pools.
- No backwashing requirement saves hundreds of gallons of water and money per year.
- Constructed of the most durable materials for the toughest applications and environmental conditions, including in-floor cleaning systems
- Single locking knob securely fastens head to filter tank, eliminating bolts or clamps
- Long lasting, extra-large cartridge element with precision engineered core provides maximum flow and efficiency
*Note : At the time of this writing Amazon has these filters with the title of SwimClear Plus but the listing is actually for StarClear Plus models. The correct heading is shown in the description portion of the listing. It’s confusing and I’ve contacted Amazon informing them of this error in the listing. So, be aware if you intend to purchase through Amazon.
- Hayward C751 : 75 sq.ft.
- Hayward C900 : 90 sq.ft.
- Hayward C1200 : 120 sq.ft.
- Hayward C1502 : 150 sq.ft.
- Hayward C17502 : 175 sq.ft.
- Hayward C2002 : 200 sq.ft.
✓ View or download the BROCHURE for the Hayward StarClear Plus pool filter series.
The Hayward StarClear Plus series has a single piece injection-molded base and body, using reinforced thermoplastic. The result is a unit that looks clean and neat and it is exceptionally robust. The filter tank should last a lifetime. It contains one cartridge element with an extruded core, this simply means that the core is stronger because it’s a one-piece unit.
The head of the filter can be removed for uncomplicated access to the cartridge. A single locking knob is used at the top of the unit to loosen and securely fasten it. That’s it, no additional bolts or clamps are used. An advantage of this set-up is that the filter head can be rotated to position the pressure gauge and manual air relief valve any way you need them to be. I also like that it’s a more secure fitting compared to using a belly clamp.
Opening and closing the unit when washing the cartridge cannot be more convenient. After washing the cartridge, it’s better to let it dry out before you replace it. In doing so, any remaining bacteria and algae will be killed. While drying out the cartridge, you can set the by-pass valve to circulate the water without passing through the filter. If your filtration system does not have a bypass setting, you might want to consider a second filter cartridge that can be used while the other is drying.
StarClear Plus pool filters are available with a 75, 90, 120, and 175 square foot filtration area. Working with the recommended size of 100 square feet to 10,000 gallons of pool water, the series can handle from 7,500 to 17,500-gallon pools. Flow rates range from 75 GPM for the smallest unit to 175 GPM for the 175 square foot model.
Uses four, non-woven, polyester cartridges. Best Pool Filters for Inground Pools.
- Large filter area for increased dirt capacity
- Corrosion-resistant, injection-molded, fiberglass-reinforced, polypropylene filter tank
- Uses four, nonwoven, polyester cartridges
- No backwashing
- Easy to clean : Remove the cartridges and rinse with a garden hose
- 100% drain clean-out port
- Continuous High Flow Internal Air Relief
- Balanced hydraulic flow
- 100% factory tested
✓ View or download the MANUAL for the Pentair Clean & Clear Plus.
- Pentair CCP240 (160310) 240 sq.ft. – 90 GPM
- Pentair CCP320 (160340) 320 sq.ft. – 120 GPM
- Pentair CCP420 (160301) 420 sq.ft. – 150 GPM
- Pentair CCP520 (160332) 520 sq.ft. – 150 GPM
The Pentair Clean & Clear Plus Cartridge filters (CCP240, CCP320, CCP420, and CCP520) have an injection-molded one-piece body to make it strong and seamless. Pentair uses fiberglass-reinforced, polypropylene for the construction of the filter tank. This means that it’s corrosion and impact resistant. The cartridge assembly uses four, nonwoven, polyester cartridges to handle bigger pools with ease.
VIDEO | See how easy it is to clean the cartridge filters
The Pentair has a waste drain plug at the bottom of the Clean and Clear. This filter also splits in the middle by removing the clamp holding the band around the middle. The advantage is that you have straightforward access to the cartridges.
It looks clean, uncluttered and neat and it should remain that way. Pentair has a good reputation as a quality brand. Should you need a dealer, a locator on their website will help you find a trusted Pentair dealer or technician near you.
The Clean & Clear Plus series is not recommended for flow rates above 150 GPM. This series is available in sizes from 240 to 520 square feet of filter area, so the filters are suitable for 24,000 to 52,000-gallon pools.
Large Capacity Filtering — Four polyester cartridge elements. Best Pool Filter for Inground Pools.
- Large-capacity cartridge filter
- No backwashing
- Rinse the filter elements with your garden hose, saving you up to 2,500 gallons of water every season.
- Choose from 225, 325, 425 or 525 square feet of heavy-duty, dirt-holding capacity for extra-long cleaning cycles
- SwimClear doesn’t require a multi-port valve, thereby using less electricity.
✓ View or download the BROCHURE for the Hayward SwimClear pool filter series.
- Hayward C2030 — 225 sq.ft. (84 GPM* / 318 LPM)
- Hayward C3030 — 325 sq.ft. (122 GPM* / 462 LPM)
- Hayward C4030 — 425 sq.ft. (150 GPM** / 568 LPM)
- Hayward C5030 — 525 sq.ft. (150 GPM** / 568 LPM)
- Hayward C7030 — 700 sq.ft. (150 GPM** / 568 LPM)
The SwimClear series (C2030, C3030, C4030, C5030 and C7030) uses a durable glass reinforced co-polymer filter tank. A cluster of four reusable polyester cartridge elements is used to improve its flow characteristics. It’s a big filtration unit, and it does a big job too, it’s designed for large pools, up to 75,200 gallons.
VIDEO | Learn more about the Hayward SwimClear
The unit also splits in the middle to provide easy access to the cartridges. Trapped air is removed by a manual air relief that’s activated with a quick quarter turn. A heavy-duty, one-piece clamp securely fastens the tank top to the bottom. It has a tamper-proof latch so that it cannot be accidentally opened. This safety feature is very important because the filter operates under high pressure. After servicing the unit, you will find that the tank top and bottom are self-aligning, so it’s quick and easy to put the filter together again.
Click image for full details on all the great features of the Hayward SwimClear
The effective filtration areas of the units range from 225 to 725 square feet, making the filters suitable for pools from 22,500 to 72,500 gallons. The flow rate of the series range from 84 to 150 GPM.
Best Sand Pool Filters
— for Inground Pools.
We’re going to review two ranges of sand filter from Hayward. Both open at the top and use a flange mount with a clamp band to secure the flange to the drum. This has the advantage that the drum is very robust and the internal piping is simplified.
Both the Hayward ProSeries and ProSeries Plus sand filters are available as Side or Top Mount sand filters. It means the unit is available with the control valve mounted at the top flange or it is mounted to the side of the filter tank. It is indicated in the last two digits of the model number, it will either end with S or SV for the side mounted valve units and with T or T2 for top mounted control valves.
The top mounted control valve piping enters the unit through a flange at the top of the unit. The valve assembly rotates a full 360° to simplify the plumbing, making for an incredibly easy installation. This configuration does have a disadvantage in that the top valve system must be removed when replacing the sand. Though you only have to do this after many years, so it won’t be a huge inconvenience. Therefore the piping must be flexible, or it must be clamped in place and not glued.
Sand Filters — Top Mount & Bottom Mount models available : Best sand filters for inground pools
- Durable corrosion proof materials for dependable all weather performance
- Large pressure sand/water drain for rapid winterizing or servicing
- Top-mount models are available with 7-position or 6-position VariFlo control valve
- Side-mount models are available with 6-position VariFlo or 2-position slide valve
Top Mount Pool Filters:
- Hayward S220T2 : Sand Required = 250 lbs. — 2″ Vari-Flo
- Hayward S244T2 : Sand Required = 300 lbs. — 1.5″ Vari-Flo
- Hayward S270T2 : Sand Required = 350 lbs. — 2″ Vari-Flo
- Hayward S310T2 : Sand Required = 500 lbs. — 2″ Vari-Flo
- Hayward S360T2 : Sand Required = 700 lbs. — 2″ Vari-Flo
- Hayward S220T : Sand Required = 250 lbs. — 1.5″ Vari-Flo
- Hayward S244T : Sand Required = 300 lbs. — 1.5″ Vari-Flo
- Hayward S270T : Sand Required = 350 lbs.— 1.5″ Vari-Flo
✓ View or download the MANUAL for the (TOP MOUNT) Hayward ProSeries inground pool filters.
Side Mount Pool Filters:
- Hayward S210S : Sand Required = 200 lbs. — 1.5″ Vari-Flo
- Hayward S244S: Sand Required = 300 lbs. — 1.5″ Vari-Flo
- Hayward S244SV : Sand Required = 300 lbs. — 2″ Slide Valve
- Hayward S244SLV : Sand Required = 300 lbs. — Not Included*
- Hayward S310S : Sand Required = 500 lbs. — Not Included*
✓ View or download the MANUAL for the ( SIDE MOUNT) Hayward ProSeries inground pool filters.
The filter tank of the Hayward ProSeries is a one-piece unit, the only opening is at the top. It’s molded from rugged, reinforced thermoplastic. The coating is colorfast and performs well in all weather. If you follow the instructions, it is virtually foolproof and it will probably provide a lifetime of excellent service.
Hayward ProSeries S244S | Side Mounted Model
A diffuser at the top of the sand ensures even water distribution over the top of the sand bed. The seven-position backwash control valve is mounted at the top too.
The flow rate of Hayward ProSeries varies depending on the pipe size, from 20 GPM using 1” pipes to 160 GPM with a 3” pipe diameter. Full instructions are available in the user manual. The biggest model is roughly 24” in diameter with an effective filtration area of 3.1 square feet. It’s suitable for average to large pools up to 31,000 gallons.
36-inch, 130 GPM professional quality pool sand filter.
Unique design is intended to meet the needs of the most demanding applications, such as : large residential pools, semi-commercial pools, in-floor cleaning systems, solar heating systems and water features. The striking spherical tank design serves an important function — it evenly distributes the high pressure and stresses associated with demanding applications. Absolutely, the best pool filter for inground pools. Worth the money!
- Large pressure sand/water drain for rapid winterizing or servicing
- Optional valve and coupling selections for plumbing ease and versatility
- Precision engineered umbrella-fold self-cleaning laterals for balanced flow and backwashing
- Efficient, Multilateral Underdrain Assembly
- Optional Valve and Coupling Selections for plumbing ease and versatility.
- Totally Corrosion-Proof Base is rugged and attractively styled to provide strong, stable support
- Integral Molded Drain Plug for easy draining of tank, without the loss of sand.
- Unitized, Corrosion-Proof Spherical Filter Tank is molded of rugged, color-fast polymeric material for maximum strength.
- Automatic Air Relief purges any trapped air during operation of the filter system
- Integral Top Diffuser ensures even distribution of water over the top of the sand media bed. All internal piping is 2” to give smooth, free-flowing performance.
- Durable Flanged Inspection/Access Cover provides convenient access to top of filter
- Manual Air Relief for easy, manual release of air from system.
Two Models in the series :
The Hayward ProSeries Plus is a bigger version of the ProSeries. The tank design is the same as the ProSeries. The corrosion-proof base is rugged and attractively styled so it will not only provide stable support, but makes it a good-looking unit.
Diagram of All the Great Features of the Hayward ProSeries Plus
A manual air relief valve makes it easy to release air from the system. It uses the same top-mounted control valve on a flange assembly with a top diffuser distributing the water over the top of the sand media. It has a 2-Inch, seven position Vari-Flo control valve at the top like the smaller units.
A total of 500 to 700 pounds filtration sand is required in this big sand filter range. It has an active filtration area of 4.9 square feet for the smallest model up to 6.5 square feet for the biggest one. For most residential pools, I recommend using the smaller unit, the S360T2 with a roughly 30-inch diameter tank, which is a 4.9 square feet filter surface area. The biggest unit will service a pool of 65,000 gallons with ease. For all tank sizes you will obtain 80 GPM flow using a 2” pipe. Almost four times the flow rate of the Pro Series.
Unique folding ball joint design allows lateral assembly to be easily accessed for simple servicing.
Control Valve Options (Hayward ProSeries Plus): 2”, 7-Position, Vari-Flo; 2”, 2-Position Slide Valve; or 11/2” SKT x 2” SLIP Connectors for Multiple (Tandem) Filter Installations.
Best Pool Filters using D.E.
Also known as Diatomaceous Earth, D.E. or diatomite powder filters. Diatomaceous earth powder used in these pool filters and is derived from tiny fossilized exoskeletons of algae-like water plants called diatoms. We’ll review one Pentair range and one Hayward range that both split in the middle with a band to lock the two halves together.
The big difference between the two manufacturers is the way they approached the assembly of the powder elements. The Pentair splits in the middle, and a straightforward assembly of four filter cartridges and two manifolds. It has a maximized filter surface area, trapping more dirt for longer. This means that it can be used for longer periods between cleaning. The internal flow path maximizes filtration and improves backwashing efficiency. This is a good way of doing things, and the internal components are reduced to the cartridges and two manifolds. It’s not a regular cartridge filter, the D.E. powder coats the cartridges to become the filtration media.
The Hayward ProGrid uses seven filter elements in a filter element cluster assembly with locators and manifolds. This is a complex assembly with lots of parts, and it looks quite fragile too. Washing it will not be as quick and convenient as the four cartridges of the Pentair range. Another concern is that there are a lot of internal seals and gaskets which can cause D.E. leaks when they fail.
I prefer the Pentair Quad D.E filters because of their much simpler internal configuration. The more straightforward installation with fewer internal seals and components are bound to be less prone to D.E. leaks. Washing the internals is a simpler operation on the Pentair, and you do not need to remove the filtration media to clean it.
Pentair Quad D.E pool filters (3 sizes)
- Pentair QUAD 60 — (188592) 60 sq.ft. (filtration area) up to 32,400 gallon pool.
- Pentair QUAD 80 — (188593) with 80 sq.ft. (filtration area) up to 43,200 gallon pool
- Pentair QUAD 100 — (188594) with 100 sq.ft. (filtration area) up to 54,000 gallon pool
- Four large-capacity cartridges provide maximum filter surface area for greater dirt-trapping capacity and longer periods between cleanings
- Unique internal flow path ensures optimum filtration and backwashing efficiency
- Chemical resistant, fiberglass-reinforced polypropylene tank for exceptional strength and long life
- Three cleaning options: backwash and recharge like a traditional D.E. filter, remove and rinse off the cartridges, or simply remove the lid, leave the cartridges in place, open the drain plug and rinse.
- Water flows through the Quad D.E. Cartridge Style Filters so efficiently that your pump will use less energy.
- Fiberglass-reinforced polypropylene tank for long life—will not corrode
- 2” plumbing connections for maximum flow
- 1 ½” drain for easy and efficient cleanout and 100% draining
The backwash control valve kit is not supplied with the filter and must be purchased separately. You can choose between a seven-position control valve and the push-pull backwash valve.
The fiberglass-reinforced polypropylene tank is pool chemical resistant, it will last a lifetime. The cartridge elements are easy to remove for effortless maintenance.
You have three options for cleaning the system: You can backwash the system like most D.E. systems, or remove the cartridges and rinse them. Then there is the last option which I really like. You remove the lid but leave the cartridges in place, open the 1½” drain plug at the bottom of the filter and rinse. It is advantageous because the cartridges are not handled and they should last longer. Of course, you still have to replenish the D.E. powder after washing the cartridges.
2” plumbing connections are used, so make sure it matches your plumbing, or make use of the correct size adapters. The flow rates range from 120 to 160 GPM. The Quad D.E is a high-performance swimming pool filter, any model is fit for a pool that’s 25,000 gallons or more.
Visit the Pentair site to learn more about their extensive line of pool filters.
Hayward ProGrid Vertical Grid D.E. filters
Large-capacity performance for pools and spas of all types and sizes. Best inground filters for inground pools.
Models — Hayward ProGrid (DE)
- Hayward DE2420 : Filtration area = 24 sq.ft. — 3 lbs. (of D.E.)
- Hayward DE3620 : Filtration area = 36 sq.ft. — 4.5″ lbs. (of D.E.)
- Hayward DE4820 : Filtration area = 48 sq.ft. — 6 lbs. (of D.E.)
- Hayward DE6020 : Filtration area = 60 sq.ft. — 7½” lbs. (of D.E.)
- Hayward DE7220 : Filtration area = 72 sq.ft. — 9 lbs. (of D.E.)
- High capacity, rapid release manual air relief valve bleeds air with a quick quarter turn of the lever.
- Self-aligned tank top and bottom make access to servicing the grid elements fast and simple.
- Bulkhead fittings and union locknuts
- Full-size 1½” integral drain
- Heavy-duty, tamper-proof, one piece flange clamp securely fastens tank top and bottom.
- High impact grid elements designed for up-flow filtration and top-down backwashing for maximum efficiency.
- For both commercial and large residential applications and years of non-corrosive, trouble-free performance.
Made from the most durable materials to meet the demands of the toughest applications and environmental conditions
- Heavy-duty, tamper-proof, one piece flange clamp securely fastens tank top and bottom and allows quick access to all internal components
The ProGrid (DE2420, DE3620, DE4820, DE6020 and DE7220) D.E. filter tank is constructed of Perma Glass XL. This is a glass reinforced copolymer, ensuring that the units are strong and durable. So you can be sure they’re going to last a long time. The ProGrid filters are available with multiport and slide valve options. Note that the valve is not included with some units, it’s best to make sure when you buy it.
These ProGrid filters have an indicator gauge that shows the pressure and it indicates the cleaning-cycle, so it’s immediately clear when a backwash is needed. The convenience of this system is fantastic and will make things much simpler. I love it.
The tank splits in the middle, and the top and bottom will automatically align when fitted together – another great design feature. A heavy-duty, one-piece flange clamp securely fastens the tank top and bottom. It’s easy to remove and makes access to the grid elements fast and simple. My only complaint would be that I don’t like the complexity of this assembly. The high-impact grid elements are used for up-flow filtration and top-down backwashing. It makes a lot of sense, dirt will flow better when washed downward with gravity.
Hayward DE7220 ProGrid D.E. Pool Filter
The DE2420 has an effective filtration area of 24 square feet and a flow rate of 48 GPM. The DE7220 one has 72 square foot filter area and a flow rate of 144 GPM. As always, I recommend that you buy the biggest that you can afford and at least the DE2420. If your pool is over 25,000 gallons, go with at least the DE6020, the 60 square foot filter.
Visit the Hayward site to learn more about their extensive line of pool filters.
Matching the pump to the filter and pool
The maximum recommended working pressure for most filters, measured at the filter, is 50 psi. If your pump delivers more than that, you must replace it with a pump of the correct size. The lifespan of an incorrectly sized pump and the filter is greatly compromised. It will tend to vibrate, the seals will not last as long as they should, and cavitation can shorten impeller life. The filter will be less efficient because the water is forced through at a higher rate than it was designed for. Sand filters may create “channels”. This happens when the water force creates holes (channels) in the sand and it streams right through the sand. The result is that the sand no-longer filters the water as it should.
An important consideration when replacing a filter, using an existing pump, is to ensure that the pump is matched to the filter. Keep in mind that sand filters use flow rates much lower than cartridge filters.
The proper flow rate of each filter is available in the user manual, and I’ve mentioned this when reviewing each of the products. Most centrifugal pumps used at a reduced flow rate will be less efficient, wasting money. It can cause noise, vibration, reduced bearing life, seal failures, cavitation and mechanical damage. A recirculation by-pass line can be a solution. It will increase the flow through the pump but lowers the flow through the system. Another solution is to install a variable speed pump. If you experience this sort of problem or even suspect so, consult a qualified pool expert.
Sand vs. cartridge vs. D.E. (advantages/disadvantages)
The only filters I ever owned have been sand filters. They were much bigger than what was recommended and I’ve always been very proud of my clean, sparkling pool. Personally, I can only speak about the sand filters, and I believe that you can get excellent results from them. The “wasted” pool water when backwashing the filter was a concern to me because I live in a water scarce area. The problem with the backwash water is that it contains pool chemicals, so I did not want to pump it into the garden untreated. I backwash the water into an open container and leave it there until the next cycle to let most of the chemicals evaporate. Just before the backwash I pump it into the garden and have experienced no problems. If you live in a water scarce area or hate the idea of ‘losing’ the water, it’s worth considering.
When using a D.E. filter, the same system works, the D.E. settles at the bottom of the open container, and it won’t harm your plants. When backwashing a D.E. filter, you have to replenish the used D.E. powder in the filter. Although it’s a simple enough operation, it differs from the sand filter and it’s an ongoing expense.
Note that most cartridge filters only filter to the same size particles as a sand filter. The greatest advantage of cartridge filters is that the filters can be washed over and again, and the flow rate is a lot higher. An appropriately sized filter will clean the pool in a shorter time than the other two models, so it saves some electricity. But it involves more work compared to a sand or D.E. filter.
All types of filters tend to clog up faster when treating a pool at the beginning of the season. The cartridge filter must be removed and washed, the sand and D.E. filter backwashed and the D.E. powder replenished. Compared to D.E. and cartridge filters, sand filters are the least expensive, and some argue that it’s the easiest to maintain.
To my mind, the sand filter wins, and to top it all, if you use one of the alternatives to sand like Filterglass, it’s an all-out winner.
Detailed discussion of each filter type
Sand Pool Filters
A particular grade of sand is used in a pool sand-filter. Commonly #20 silica sand, 0.017 to 0.02 inch diameter grains are used to trap 20 to 100-micron dirt particles. As the water circulates through the filter, debris settles down in the sand. This sediment closes up the gaps between the sand particles and the filter traps even finer dirt particles from the pool water. This explains why the sand filter delivers sparkling clear pool water. The dirt that collects causes the water pressure to increase, when the pressure reaches 8 to 10 psi higher than when it was clean, it’s time to backwash the filter.
Pool Filter Sand Problems
Pool filter sand often collect small clumps of oily gunk caused by using Biguanide chemicals, such as Soft Swim or Baquacil. It requires an annual cleaning of the pool filter sand with sand filter cleaner to prevent it from “gumming-up.” High amounts of bather oils can also gum-up a sand bed. Enzyme pool treatments can help control oil problems in pools.
Another problem is when the water creates channels through the sand, and it’s streaming right through without going through the sand. When you find that you often backwash without the water pressure changing much or the wasted water looks quite clean, it may be a symptom of filter channeling. It’s often caused by heavy organic gunk building up in the filter sand and clumping it together. In hard water areas, calcium deposits can “calcify” the sand, literally turning the filter sand to sandstone. Water balance problems or an oversized pool pump can also contribute to pool filter sand deterioration.
Your first course of action should be to remove the sand and wash it thoroughly. The laterals at the bottom of the tank become brittle as they get older, and it may be wise to replace them. You may have to consult a pool expert for your channeling problems, merely replacing the sand or the filter will not solve the problem. The water must be tested to determine what is causing the build-up. It may result from high levels of aluminum sulfate or “alum,” D.E. powder, AquaPerl or clarifiers that was used to clear up the pool water. If it’s an old problem, and cleaning does not solve it, the pump size should be checked.
When backwashing, oils and gunk trapped in the top 2 inches of the sand bed can cause the water to rush up the sides without cleaning the sand. It’s another form of channeling with almost the same symptoms. The backwash looks clean but the pressure remains high when you start the filter. Sand filter cleaners or enzymes are helpful products to remove the gunk. Replacing just the top 25% of your filter sand with fresh pool filter sand is another solution.
Before you remove the filter sand, block the standpipe or side scoop, so you don’t spill sand into it. Stuff a rag or plug into it. You may use a shop vacuum to suck out the sand or use something to scoop it out.
If you decide to remove all the sand, be very careful not to knock or break the laterals at the bottom of the tank. Getting every bit of sand out is not necessary. After removing the sand from the tank, add enough water to cover the laterals so that when you pour sand into the tank, it in won’t crack them.
Filter sand blowing into the pool
Right after backwashing, the multiport dial should be set to the rinse position first, run for a few minutes, then finally to the filter position. If you’ve done this and sand is blowing into the pool, you need to open up the filter and examine the laterals. Laterals are the perforated pipes at the bottom of the filter and can be damaged easily. It’s quite possible that one or more of them were broken by adding sand without first adding water to the filter. Also make sure that the laterals fit nicely to the manifold so sand cannot enter there. Remove and examine each lateral to be sure.
Make sure that you use the correct size sand in the filter. It must be sand that’s graded for pool filters or one of the alternatives. If you are not sure that the sand is still in good condition and you have already checked the internals of the filter, take a sample to the supplier and ask them to advise you.
Sand Filter alternatives
If you currently own a sand pool filter but you think it should perform better, and that’s why you’re reading this, you’ve hit the jackpot.
Before you replace a perfectly good sand filter body, I recommend that you consider the pool sand alternatives.
- Sand filters down to 20 to 40 microns
- ZeoSand filters down to 2 to 5 microns
- Filter glass filters down to 2 to 5 microns
- Polyballs filters down to 10 microns
- E. filters down to 2 microns
- Cartridge filters filter down to 25 to 100 microns
D.E. is no longer the most effective, and it must often be replenished. Sand and its alternatives last 5 to 10 years.
What is ZeoSand?
ZeoSand, or ZeoBest, is comprised of 100% natural zeolites. You typically find zeolites in volcanic rock. The shape of the ZeoSand looks like a 3D honeycomb, making it very low in density, providing a greater surface area per grain than traditional filter sand. Because ZeoSand settles closer together than sand does, pool owners use less ZeoSand in their filters than filter sand. You will backwash less frequently and save money on water consumption. ZeoSand is all natural and environmentally friendly, too.
Filter glass is another viable replacement for pool filter sand. It’s expensive, about twice the price of Zeolite and pool filter sand. The filtering glass is crushed pieces of recycled glass that are smooth to touch. The shape of each particle prohibits channeling problems within the filter. Filter glass has a slight negative charge which aids in reducing iron and magnesium. You will require 20% less than traditional filter sand, but it works out 63% more expensive. Filter glass is compatible with chemicals like sanitizers, clarifiers, and metal removers. In the long run, it is a cost-effective solution. The capital outlay may seem high, but this is by no means a lot of money.
What Are Polyballs?
Polyballs, or polyester balls (Filterballs Blü10), can be used instead of sand to filter your dirty pool water. One pound of Filterballs Blü10 is equivalent to 100 pounds of #20 silica sand, so you use a lot less. The price for 1 pound of Filterballs Blü10 is about the same as 100 pounds pool filter #20 grade silica sand.
It seems that filter sand will last a lot longer than the poly balls and it’s not clear that the balls are compatible with clarifiers.
How to get sparkling clean pool water
For sparkling water, we need a few things working together in harmony. The pool chemicals must be balanced, filtration must be good, the pool must be cleaned daily, surface skimming must be effective, and the water must circulate for long enough. If one of these requirements is lacking, the water will not sparkle. If you do all this and find that the pool is still lacking that sparkle, you may have a filter problem or a pump that does not match your filter or pool size.
So, let’s eliminate the pump, as I explained previously it’s possible that the filter is undersized. Use the guidelines we gave you and do your own estimate for a filter size. If it’s undersized, do yourself a favor and upgrade it. But, while you are busy, look up the specifications of the pool pump as well, its flow rate must be less than the maximum flow rate of the filter you use. If you feel you are not qualified to make this decision, get some help.
Many sand pool filters are installed by a pool owner or builder looking for the cheapest filter and are, therefore, undersized. This ends up costing more money in the long run.
It’s not only the size that affects your choice of filter. The amount of debris entering the pool, how often the pool is used and the how diligently the chemical maintenance is done are all important considerations. Dirtier and more active pools need more filtration, therefore, larger filters work better here.
Cartridge Pool Filters
Cartridge filters have mostly been used in smaller above ground pools and spas. Bigger units are available for inground pools and usually use four filters. The best pool cartridge filter elements trap debris that’s 25 to 100 microns in size. Usually, when the pressure gauge indicates 8 – 10 PSI above its clean reading, it’s time to clean the filter. To do this, you remove the cartridge from the tank. You need to drain the tank first, then split it to remove the cartridges. Then it’s simply hosed thoroughly from top to bottom with a garden hose. Once cleaned, you should inspect the cartridges for any damage like small holes or failing bonding material to determine if it should be replaced.
If you use a filter that’s a bit undersized or a just fit and it has to contend with some algae and lots of tree debris, etc. then you will open the filter almost monthly, and the cartridge may only last one to two years. Appropriately sized cartridge filters can last up to six months between cleaning, and the cartridges can last more than five years.
The unit does not have a backwash control valve, and very few parts other than the filter cartridges, so there is little maintenance apart from cleaning the system. You only have to keep the belly band O-ring clean and lubricated and replace the filter cartridges after ten to fifteen cleanings.
When cleaning the filters, shut off the pump and use the air bleeder on top of the tank to drain trapped air and release pressure. Depending on the unit, a drain valve may be fitted at the bottom, and if it’s big enough, you might be able to wash the cartridges in the tank. If the tank drains fast enough, this is the easiest way to do it and the cartridges will last longer. The less the cartridges are handled, the better. It’s merely hosed thoroughly top to bottom and replaced if necessary. It’s a wet job, but if the filter is correctly sized, it’s a once or twice per year job. An advantage is that cartridge filter cleaning uses less water than backwashing.
Chemicals like calcium and bather oils sometimes become embedded in the pleats of the pool cartridge filters. If these contaminants are difficult to remove with a standard hose cleaning, or you are cleaning the cartridge filter every 3-4 days to keep the pool pressure down, then cleaning the cartridge chemically with a solution like TSP, or one of the many chemicals labeled pool filter cleaner, is another option. After hosing, soak the cartridge in the solution for 24 hours and rinse it again.
When satisfied that the cartridges are clean, place them somewhere to dry completely for 24 hours. It will also kill any microscopic organisms. If you do not have a second set of filters, bypass the filter to recirculate the water. If necessary, you can operate the pool filter without the cartridge inside the tank, but be sure to remove all internal parts and then assemble it tightly.
If you experience a problem where debris bypasses the filter cartridge, then the filter and internal parts such as baffles or diffusers may be damaged.
How long should I run my Cartridge pool filter each day?
It depends on the weather, the pool environment, your filter and external variables. Is the filter possibly undersized or is it very old? If this is true, you should consider selecting one of our best pool filters and replace it. If your filter is still performing as it should, it may be one of a number of factors.
If the pool is used a lot and lots of debris enter the pool, its midsummer and temperatures are high, the filter has to work very hard. If you use a suction side pool cleaner, you have to run it a lot longer, from 13 to 16 hours a day. The demand for chemicals is also high in this situation, so it may be necessary to attend to it daily.
If you are new to pool maintenance, it’s best to monitor it daily and to experiment with the time that your pump runs. While doing this, you have to make sure that the chemicals are within the recommended levels. You will soon find the optimum time to run the filter system. You will have to adjust to changes in season, but that will become a natural thing.
D.E. pool filters
If you have a Diatomaceous Earth (D.E.) pool filter, you should be content. It’s a good pool filter and it should keep your water clean and healthy. D.E. filters require a little more work than sand or cartridge filters. The extra work is due to their operation and using the Diatomaceous Earth as the filtration medium. The filters are backwashed when the pressure rises to the recommended pressure levels. Backwashing is the same simple operation needed for sand filters. The additional bit of work is to add the D.E. powder.
When the filter requires more frequent backwashes than normal, or at least once per year, you have to open the filter to wash the grids with a hose. On some makes, the cartridges/grids may be left in the drum whilst doing this because the water outlet is big enough to drain the water. On most units, more work is needed to remove the cartridges for a wash and inspection.
Let’s take a look at some common D.E. pool filter problems. You should be able to attend to all of them yourself although you may need some parts from the dealer at times.
— Leaking Clamp Band and other leaks
This problem can occur on all types of filter units that split in the middle, not only D.E. filters. If you find that the filters leak at the clamp band, it’s due to one of two things. The large O-ring seal is the primary seal against leaks. If it’s clean and not distorted or cracked, it should do the job. Where it sits between the top and the bottom sections of the filter body it must be clinically clean with no dings or scratches. Any sand, dirt or irregularities will cause the filter to leak due to the high pressure inside. Start with a clean and lubricated O-ring. Dirty, dry O-rings don’t seal, and the seat must be as-new and lubricated. Don’t go overboard with the lubrication, a thin layer is all that’s needed. When tightening your clamp band, it must be centered over both tank halves.
I find that it helps to make sure the inside of the band and the area where it seats are also spotless and lubricated. When you tighten the band, it must be able to move on the cylinder halves. The two halves must be able to position correctly so tapping the band lightly while tightening it with a socket wrench helps as well. Tighten until the spring windings touch, never more than that. The tapping will help to seat the clamp over the tank halves.
Wrap the threads of the drain plug in a clockwise direction with Teflon tape before you screw it in. It’s possible that an O-ring seal is used and then it must be lightly greased with pool lube as well. It helps the seal to seat well when tightened down.
If the air bleeder on top of the filter tank drips water, there is usually an O-ring or some seal at the air relief stem that is failing. It’s possible that the assembly is cracked, so inspect it thoroughly before you remove it for servicing.
If the pressure gauge assembly leaks, it is likely that the seat is cracked around the screw fitting. Super glue can sometimes be useful if you squirt some in while the crack is open. But the pressure inside the tank must be released and the crack allowed to dry completely. After inserting the glue, you unthread the pressure gauge and allow some time for the glue to reach maximum strength. The final step is to reseat the gauge and test the repair.
If you have a multiport control valve and you find that water is leaking from the backwash port when the valve is in the filter position, the spider gasket is most likely unseated or damaged. To replace it, you have to remove the top of the valve and inspect the gaskets. If your filter has a push-pull slide valve, you must open it and examine the piston O-ring for wear.
— D.E. leaking from Manifold
The main thing to remember about D.E powder is that the particles are very small and it will easily go through a crack or pass a bad seal. So, if you find that the powder finds its way out, try to think back along the water passage from where you see it at the filter. If it finds its way into the skimmers, it happens during backwashing. The powder is forced past the gaskets or an O-ring inside the filter valve.
If you see the power as dust where the water is fed back into the pool during normal filtering, it’s obviously coming from the filter grid or internal piping seals. The water is forced from the outside of the grid through the powder and the grid. Then it should be clean, but in this case some powder is coming with. The only solution is to stop the pump, release pressure, drain the filter, open it and inspect the grid for small holes. Also, check the PVC standpipe used in most D.E. filters. If the thin O-ring where the standpipe connects to the manifold goes missing or breaks, small amounts of D.E. and dirt will find their way into the pool.
There is no rocket science here. The powder can only find a way out where there is a leak.
— D.E. leaking from Grids
Remember that D.E. filters use D.E. grids that are covered with the D.E. powder to act as the filtration media. If the powder leaks into the pool, it’s possible that small holes have developed in the fabric, or the stitching or seat material on the grids can become bad. You’ll have to open the unit and inspect all the internals for signs like a loose grid assembly, with the thru-bolts not fully tightened. Look for incorrectly spaced grids that can allow D.E. powder to bypass through small holes where the grid inserts into the manifold. Damaged D.E. Grids can be replaced individually, or you can buy the entire grid set.
— High pressure indicated after a backwash
Finally, D.E. Filter grids can become clogged with oils and minerals, requiring a lot of pressure to force the water through. This will be indicated by a higher than normal pressure after a backwash and with new powder has been added correctly. It may mean that you need to clean the filter grids with a D.E. filter cleaner to remove the oils and minerals that are clogging the grids. If the gauge reading is still high after that, it’s possible that the gauge is no longer accurate, so you may need to replace it. Or the grids must be replaced with a new set.
How to Keep Your pool clean
Be sure to operate your filtration system long enough each day to obtain at least one complete turnover of your pool water. To determine that, you will have to do some math. The size of the pool in gallons divided by the gallons per minute flow rate of the system. E.g., 30,000 gals. ÷ 80 GPM÷ 60 min. = 6.25 hours. But that is the lower limit, it may be better to run the system longer than that.
The chemicals used to control the algae in the pool water can be dangerous. Pool chemicals can irritate your eyes, nose, and throat and it can cause skin problems. It’s crucial that you know how to handle chemicals and that the pH of your pool is balanced correctly. Read and follow the instructions on the chemical packaging and test the pH level of the water regularly to ensure safe chemical exposure.
While working with the chemicals be very careful, do not inhale the fumes and do not mix the chemicals. Do not add water to concentrated chemicals, it can lead to serious injury.
Ingesting undiluted chemicals can be fatal due to the caustic nature of these chemicals. Take care to keep pets and children away from stored chemicals.