Filter Problems

Pool filters help maintain clean water by removing particles and small debris from pool water. When a filter problem occurs, the operation and safety of your pool are compromised. Recognizing telltale signs that something is wrong with your filter and knowing how to fix it will depend on whether you have a sand, DE, or cartridge filter.

Jump To Section:

Sand Filters
     Common Sand Filter Problems
     How to Replace Filter Sand
     How to Remove Sand From Bottom of Pool
DE Filters
     Common DE Filter Problems
     How to Replace DE Powder
     How to Get DE Powder Out Of Pool
Cartridge Filters
     Common Cartridge Filter Problems
     How to Replace a Filter Cartridge


Sand Filters


Common Sand Filter Problems


Cloudy Water

Sometimes, cloudy water can be caused by a dirty filter, which is evident when the filter pressure is high. When a filter pressure reading is 8-10 pounds higher than the pressure reading following cleaning, the filter is dirty and requires backwashing.

If that doesn’t restore proper pressure, you could have a misfunctioning gauge, bad sand, a multiport valve issue, or a filter obstruction.

Sand in the Pool

If sand frequently enters your pool, you likely have broken sand filter internals, specifically the laterals or standpipe.

Empty the contents of your sand filter to check your laterals and standpipe. Standpipes are durable, so if sand is in your pool, it’s usually a broken lateral causing the problem.

If any of these components are cracked or damaged, they need replacing.

Water Exiting Waste Line

If a constant flow or residual water comes out of your waste line, your multiport valve may have a spider gasket problem. To replace your spider gasket, follow these steps:

1. Check that the filter system is off and depressurized.
2. Unscrew the valve cover from the valve body, then remove the spider gasket from the valve cover assembly.
3. Clean the surfaces of the gasket groove to remove any debris. Allow it to dry completely.
4. Apply waterproof glue to the bottom of the spider gasket groove, then insert your new spider gasket.
5. Press and seat the gasket properly. If necessary, wipe off any glue that overflowed.
6. Reattach the valve cover and turn the handle to the nearest available setting – either rinse or filter.
7. Wait at least 24 hours for the glue to fully cure.

If a broken valve spring is to blame rather than a spider gasket, your multiport valve handle will feel loose. To replace, open up your valve assembly and switch the old spring with a new one.

Improper Filtering

If dirt and debris continue to flow back into your pool even after backwashing, there could be several reasons to blame:

  • If you haven’t changed your sand in the last five years, your old, worn-out sand is likely the cause.
  • Channelling – which is when water travels through a channel in your media rather than filtering through the sand – also causes improper filtration. Your pool pump may be too big for your filter if channelling occurs. Getting a smaller pump is not recommended, so upgrade to a larger filter. For variable-speed or ECO pumps, try a low or ECO setting.
  • When your pool water has high pH levels, sand can become more like cement and require replacing.
  • Excess oils, hair, and other debris may be creating a clog (called a mudball) that backwashing cannot dislodge. Your filter media will need a filter cleaning solution. Remove the unions of your multiport, pour in the solution, and let stand for a couple of hours. Complete a backwash, then rinse. If your sand filter is hard plumbed into the pipes, apply the solution directly to your pump’s basket. Turn the filter on, and wait for the solution to be sucked into the sand filter. Turn the filter off. Wait a couple of hours, then complete the backwashing and rinse cycles.



How To Replace Filter Sand

Pool filter sand typically lasts 3-5 years. When it nears the end of its lifespan, it can no longer collect contaminants. This can lead to cloudy pool water or require more frequent shock treatments. To change your sand in the pool filter, complete the following:

1. Turn Off Your Pump and Drain Your Filter

Power off your filter and pump. Locate the drain plug on the bottom of the filter tank and remove it to allow the water to drain out. Draining can take several hours.

2. Disconnect the Multiport Valve

Remove the unions that connect the hoses or pipes to the multiport valve. For hard plumbed valves, the pipe will need to be cut. Use a screwdriver to remove the flange clamp, which holds the filter on the tank. Carefully twist, then pull up on the multiport valve to take it off.

3. Cover the Standpipe

Apply duct tape to the standpipe to prevent sand from entering.

4. Remove the Sand

Use a shop vac to remove the old sand, being careful not to damage the lateral pipes. If you don’t have a shop vac, you can use a plastic cup to scoop the old sand into a bucket. However, this is much more time-consuming.

5. Rinse the Tank

Rinse out any remaining sand from the drain hole using a garden hose

6. Fill the Tank Halfway with Water

Put the drain cap back on the bottom of your filter tank. Place a garden hose into the tank and fill it halfway with water, centring the standpipe and laterals. The water creates a cushion to protect the laterals from the weight of falling sand.

7. Add New Sand

Wear a mask to avoid breathing in dust. Refer to your filter’s manual to determine the appropriate amount of sand to add. Hold the bag above the top of the filter, then make a small slit in the bag to dump out its contents. Slowly add one bag of sand at a time.

8. Fill the Tank and Reassemble

After adding the sand, fill the rest of your tank with water. Remove the duct tape from your standpipe. Replace the multiport valve, flange clamp, and pipes or hoses. Ensure all fittings are secure.

9. Backwash and Rinse

Select the backwash setting on your multiport valve. Backwash until the filter’s sight glass is running clear. Turn the multiport valve to the rinse setting, and rinse for one minute.

10. Turn the Pump On

Select the filter setting on your multiport valve, then turn the pump on. Note your filter’s normal running pressure. When pressure is 10 psi above normal, it’s time to complete a backwash.


How To Remove Sand From Pool Bottom


1. Collect Sand

Use a pool brush to sweep all the sand to a few concentrated areas. Brush the pool walls to dislodge any sand stuck to the sides and thoroughly clean the pool’s corners.

2. Adjust Your Filter Setting

Switch your multiport valve to the waste setting so the sand will not damage your filter. Be prepared to lose a lot of pool water quickly.

3. Overfill Your Pool

Add more water to your pool before you get started to help compensate for the amount you’ll remove during vacuuming.

4. Vacuum It Up

Moving quickly, vacuum up the sand in the pool manually.

5. Add Pool Water

If necessary, fill your pool with additional water to return it to the proper level.

6. Rebalance Your Pool Water

Test and balance the water, adding any necessary chemicals.


shop vac beside pool


DE Filters


Common DE Filter Problems


DE Powder in the Pool

Torn filter or grid fabric, a cracked top manifold, or a missing air bleeder or standpipe o-ring may cause DE powder to enter your pool. An issue with your filter valve could also cause DE powder in pool water.

If your DE filter grids start to develop holes, you should replace the damaged grids promptly by following these steps:

1. Turn the pump off, then release the pressure within the filter tank by opening the air pressure relief valve.
2. Drain the filter by removing the drain plug.
3. Open the filter by loosening the clamp band with a socket wrench.
4. Remove the grid assembly out of the tank.
5. Disassemble the grid assembly by removing the nut(s) on the top manifold before gently pulling off the top. Pull out the filter grids from the bottom and discard them.
6. Reassemble the grid assembly with the new grids. Place the top manifold on the ground upside-down to make the process easier. Start by placing the partial grid in front of the assembly, then put the remaining grids into the manifold. Work the bottom spreader or bottom plate over the grids while lining up the cut-out in the bottom plate for the standpipe. Continue aligning the tabs of the bottom spreader plate between each of the grids until it looks symmetrical. Tighten the bolts carefully.
7. Reinstall the grid assembly back in the tank, then clean and lubricate the belly-band o-ring to create a water-tight seal. Replace the lid on the tank, then reinstall the band. Tighten down the clamp band with a wrench.
8. Turn the pump back on, then add the appropriate amount of DE powder into the skimmer. In general, you should calculate the volume of your swimming pool and divide it by five to calculate the number of DE scoops necessary.

Pool Pressure Problems

Usually, a dirty filter is the most common reason for high pressure. Simply backwash your DE filter and then recheck the pressure to see if it has returned to normal. For low pressure issues, check for an obstruction or other cause that’s preventing water from reaching the pump.

Poor Water Quality

The following are potential reasons for poor water quality when you have a DE filter:

1. A faulty multiport or push-pull valve
2. Insufficient filter run time
3. Improper amount of DE powder in the filter
4. DE filter requires backwashing or manual cleaning

Leaking DE Filter

Even though a filter leak won’t cause a considerable drop in your pool’s water level, you should try to locate the leak promptly.

When water leaks from the centre clamp, the large o-ring between the tank halves may need replacing. Ensure the clamp band is centred between the two halves of the tank and use a socket wrench to tighten the clamp. Keep the o-ring lubricated and apply some Teflon tape on the threads.

When water is leaking from the drain plug, wrap it with Teflon tape or use lube to seal the plug. Avoid overtightening the drain plug; otherwise, you may crack the underdrain assembly.

If the water leaks through the tank itself, the tank or entire filter needs replacing.

Calcium Clogged

The filter’s pressure can be affected by minerals clogging the DE filter grid fabric. Soak your DE grids in a mild acidic solution or use a filter cleaning chemical to dissolve these minerals and restore a proper flow rate.


How To Backwash A DE Filter

1. Turn off the pump.
2. Select the backwash setting on your multiport valve.
3. Turn the pump back on.
4. Backwash for at least 1-2 minutes, or until sight glass runs clear.
5. Turn off the pump.
6. Return the valve to the filter position.
7. Turn the pump back on. Release air from the air release valve.
8. Refer to the owner’s manual for the recommended amount of DE powder. Add the quantity of DE to the skimmer closest to the equipment.

Backwashing a DE filter does not remove all of the DE powder. The only way to completely remove all DE is to disassemble the filter and clean it, which should be done at least annually. After doing so, pre-coat with the entire quantity of DE as specified in your owner’s manual.


How To Get DE Powder Out Of Pool


1. Collect DE Powder

Use a pool brush to sweep all the DE powder to one area or a few concentrated areas. Brush down the pool walls to dislodge any powder stuck to the sides and thoroughly clean out the pool’s corners.

2. Adjust Your Filter Setting

Switch your multiport valve to the waste setting so the DE will not damage your filter. Be prepared to lose a lot of pool water quickly.

3. Overfill Your Pool

Add more water to your pool before you get started to help compensate for the amount you’ll remove during vacuuming.

4. Vacuum It Up

Moving quickly, vacuum up the DE in the pool manually.

5. Add Pool Water

If necessary, fill your pool with additional water to return it to the proper level.

6. Rebalance Your Pool Water

Test and balance the water, adding any necessary chemicals



Cartridge Filters


Common Cartridge Filter Problems


Pool Pressure Problems

Random or rapid filter pressure increases and low pressure can indicate a filter problem.

When the pressure is too high, your pool filter can become dangerous to operate. Usually, a filter’s optimal range is 8-15 psi, but check your manufacturer’s instructions for your specific filter’s recommended psi levels.

Rapid pressure increases are typically because of a clogged filter, which will require proper cleaning.

A low pool filter pressure is much less dangerous and can normally be resolved by locating a clog or other obstruction in the skimmer, pump basket, pump impeller, or main drain pipes. Inspect the gauge dial to see if it’s held in place properly.

Water Leaks

The thick metal band around the main body of the filter can begin leaking from high pressure or being poorly positioned. Over time, vibrations can loosen the clamp, or a lack of lubrication can create cracking.

If water leaks from the clamp in the cartridge pool filter, inspect the seal for any wear and tear and replace it if needed. To fix it, you’ll need to turn your filter off and disassemble it, removing the filter clamp band and o-ring. Complete a cleaning of these components and the tank, then reassemble the parts. Applying a lubricant to the o-ring with pool lube can help create a more secure seal.

A cracked tank, damaged valves, or damaged spider gasket seals may also be the reason for the leak. If your tank’s cracked, it will require replacing since it cannot be repaired.

Short Filter Cycles

If your filter is sized correctly, cleaning is only needed every 3-5 weeks. When there is too much flow through the filter and the time between cleanings becomes shorter, the filter may be too small for the pool, or the pump may be too powerful for the filter.

Oily Cartridges

A filter’s ability can become compromised if its pores are clogged with oils. Use a product that contains enzymes in your pool to help control oils before they reach your filter.

Damaged Cartridges

Cartridges can become cracked with age or from deadheading the filtered water (closing off all the valves after the filter). They can also become crushed when there’s too much water pressure. In either case, it’s time for a new filter cartridge.


How To Replace A Filter Cartridge

1. Turn off the pool pump.
2. Open the air relief located on top of the filter to release any vacuum in the system.
3. Place stoppers at the intake and return ports on the pool.
4. Open your filter.
5. Remove the cover of the cartridge chamber, then remove the used cartridge.
6. Install a new cartridge.
7. Replace the cover and tighten the screw.
8. Remove the stoppers from the intake and return ports.
9. Open the air release valve until the water flows through, and then close it (if available on your filter model).

Popped Tops

A filter tank’s top can blow off from deadheading or a full tank of water freezing. This dangerous problem can be avoided by closely monitoring the pressure gauge when starting your filter pump.