Swimming pool filter problems and solutions

Ned Kampmann

By reading this article you will learn about most of the common pool problems and how you can solve them efficiently. Pool filters are the most important line of defense in keeping your pool clean, so you should know about the main types: Sand, Cartridge and D.E. (Diatomaceous Earth).

Differences between filter types:


Sand filter – it can filter particles in the range from 20 to 40 microns. It is the oldest and most commonly used method of filtration and uses a special kind of abrasive sand. It is the cheapest kind of pool filtration, but it only filters the largest particles.

Cartridge – this can filter particles in the range between 10 and 20 microns. Cartridge filtration has recently become very popular, but it has been around for a long time. It works in a very similar way to the sand filter, but when water passes through the cartridge, any contaminating particles will remain inside it. All you need to do is to take the cartridge out and rinse it with a regular garden hose.

D.E. (diatomaceous earth) – this can filter the smallest particles, in the range from 1 to 13 microns. The vast majority of pool professionals advise buying and using D.E. filters if at all possible. And I personally agree with them. A D.E. filter may not be the best in terms of maintenance and it is by no means the cheapest, but it offers the best possible filtration quality.


Inground swimming pool filter problems

swimming pool cartridge filter problems

By maintaining or repairing your pool filter system at least once a season, you can prevent any kind of filter problems. However, accidents can always happen, so it’s always good to know what possible problems may arise, for example the problem of your swimming pool filter sucking air. The most common are:



This is the easiest problem to spot. There will be water under your pool filter or you’ll simply be able to hear a dripping sound if you stand near it. Try locating the leak. If you find a rusty hole in your filter tank, in most cases you`ll have to replace your tank and filter. A patch won’t last long, so it’s better to fully replace it. Another possible cause is a split tank filter. If you own this type of filter, try checking its belly band. If it’s full of debris, remove the debris, clean the O-ring and lubricate it. Reposition the O-ring and the problem is solved.

Short cycles

swimming pool pump filter problems

After you have been using your pool for some time, the problem of short filter cycles between cleanings may occur. If this is happening periodically when you are not using pool, the cause of it might be a high flow rate. There are several possible explanations for problems with your swimming pool filter motor: perhaps your pool pump is too powerful or your filter is too small for your pool (if you own an enormous inground pool, I bet on the second one). If the filtration system is appropriate for the size of your pool, try backwashing for a longer period, until you can tell that the water is clear just by looking at it. Contaminants such as algae may also cause filters of any type to work in short cycles. In this case, adjust the chlorine level to prevent a buildup of algae. Problems with swimming pool cartridge filters are commonly connected to algae growth, so ensure that you replace the cartridge as is necessary.

Filter material in the pool


This is a tricky issue. Most people think that contaminants can only get into their pools from outside, but this is not the case! Problems with swimming pool sand filters often occur. Pool filters can also be a source of dirt in your pool. If you have a sand filter or even a D.E. filter, be aware that any small filter media can end up in your pool, if something goes wrong with the filter system. If you see a small amount of sand after backwashing, don’t panic. This is normal. However, if you see a steady flow of sand into your pool, then it’s time to take measurers. Check the sand filter standpipe for a crack or the internal structure of a D.E. filter for tears.

Incorrect pressure

swimming pool cartridge filter problems

Every pool filter has a gauge. A good pool owner must control the pressure in his filter system. There are only two deviations from the norm – higher or lower pressure. The main cause of incorrect pressure is clots. To find out exactly where a clot is, you will need to check the above-mentioned gauge. If the pressure is too low, then the clot is somewhere in the system before the filter itself. And visa versa, when the pressure is too high, the clot is somewhere in the system beyond the filter. Try checking the filter for such a blockage, or the only other option is closed return valve.

Above ground swimming pool filter problems

swimming pool pump filter problems

There are no technical differences between inground and above ground filtration systems. The only thing that differs is the amount of water you have to backwash. The estimated amount for an inground pool is 250-500 gallons of water, whereas for an above ground pool it is 50-150 gallons.

Related articles