Swimming pool sand filter problems

Ned Kampmann

It goes without saying that one of the most important pieces 0f equipment in your pool system is the filter. Sand filters are designed to remove small particles and debris from the water. Most filters operate for at least for 12 hours a day, so proper maintenance is highly recommended. This article provides information on sand filter troubleshooting.

How does a sand filter work

The principle of a sand filter for a pool is as follows: the pump starts and the water begins to be absorbed into the device, where it passes through a layer of silica sand, is cleaned and is then returned back into the swimming pool. When the device becomes clogged, water is passed in the opposite direction and is drained into the sewage system. To this end, several modes of operation are provided in most models.

Swimming pool sand filter leaking

How to backwash a sand filter
The first step here is to find the leakage. In a swimming pool sand filter system there are several possible places. It could be that the body of the sand tank is leaking. In this case it really is a good idea to replace it, seeing that you simply cannot fix the leak by yourself. Water expansion during the winter season can easily crack sand filter pipes or its body. All the damaged components have to be replaced quickly to minimize the amount of water wasted. Flooding your neighborhood will cost you nerves and money, so you’d better act swiftly.

How to backwash a sand filter

Most novice pool owners are afraid of this procedure, but in actual fact there is nothing simpler. Basically, backwashing a filter means that you reverse the water flow from the pool back into the filter and send out the incoming water to the sewage system. The first step is to turn off your pump. This is a common mistake of many people that causes cracks in filter system components, so do NOT forget to turn off your pump. Secondly, set the filter valve to backwash and restart the pump. The backwash time depends on the exact model of your filter (check the user’s manual for more accurate info), but usually it takes 3-5 minutes. When this process is complete, turn off your pump and set the filter valve to ‘rinse’. To ensure that dirty water from backwashing doesn’t return to your pool, turn the pump on again for 1 minute. Stop the pump, set the filter valve to its ‘filter’ setting and that’s it. Start the pump and enjoy your pool time. These are the simple steps to backwashing a sand filter.


Why is pool water cloudy

If your pool looks green, in most cases the cause of it is algae growth. By adding more sanitizer, you can get your pool clear again. When you have shocked your green water with chemicals, it may cause the water to turn cloudy. This is the dead algae. The solution to the problem of cloudy pool water is rather simple – add more shock and clarifier to the water. This will cause any remaining particles to sink, and you can vacuum them with a pool cleaner, or if you have a sand filter for your swimming pool, it will do it for you. Just remember that at this stage you may want to leave your filter system working all day and all night until the cloudiness has completely gone. Another possible explanation for cloudy water is high pressure in the sand filter. A dirty swimming pool sand filter can cause cloudy water too. You can get info on filter troubleshooting in my article here.

How to clean a sand filter

Most devices are equipped with an automatic washing system. If not, the procedure can be carried out by yourself.
To do this, turn off the device, turn the valve to ‘flush’ mode again and turn on the pump for a few minutes. Then, turn the valve to its ‘compaction’ mode in which it should run for about a minute, then switch to the ‘filtration’ mode.
The process of filtration is important every day, and the device should not be left idle, as unwanted matter and impurities will gather in your pool.
To decontaminate the device, you should carry out the following steps:

  • Disable the device.
  • Switch the filter to its ‘backwash’ mode and turn it back on.
  • Observe the process until the cap on the valve body is clear. The procedure takes an average of about three minutes.
  • Switch to ‘Direct wash’ mode for 20-30 seconds.
  • Switch to ‘filtering’ mode.

This procedure should be carried out every week, depending on the level of contamination of the pool and how often it is used. Outdoor pools can become clogged quickly, so they need to be cleaned more often. It is important to perform sand filter maintenance on a regular basis.

Swimming pool sand filter low pressure

You may notice a substantial decrease in your pool line pressure overnight, from 15 to as little as just 5-7 psi, a low water flow rate and that your pool cleaner has almost stopped working. These are symptoms of low pressure in your sand filter. The most common explanation for this is suction problems, meaning that something has caused a blockage on the suction side of the pump. If the blockage is on the pressure side, then the gauge will show that the line pressure is too high.

Solutions for incorrect pressure in the filter system:

Check the O-ring on the suction side for leaks.
Check the skimmer or strainer basket, pump pipes and pump impeller for blockages.
The pump is too small. Read my article on pool pumps.
It may be that the pressure gauge is simply broken and that you are reading incorrect values. In this instance, you need to replace the faulty gauge.

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