Sand Pool Filter Troubleshooting and Maintenance

It is hard to understate the importance of your swimming pool’s filtration system. The filter is the primary defense against debris, algae, and harmful bacteria that would otherwise thrive in your pool water. Without a functioning pool filter, your water would turn into a cesspool of cloudy, algae-filled water.

Sand filters are one of the most common filter types. The sharp particles of specialized sand catch debris that flows through the filter and cleans the pool water. Sand filters are generally pretty reliable, but some issues can arise. So knowing how to identify and fix these issues can be very helpful.

In this article, I will go over some common issues with sand filters and discuss some helpful maintenance tips.


Main Takeaways

  • High filter pressure is generally a sign that your sand filter needs to be cleaned and backwashed.
  • Low filter pressure in your sand filter means less water is flowing through the filter, and the sand filter cannot do its job of cleaning the pool water.
  • You will not need to replace your filtration system often, but you will need to change the sand in the pool filter every couple of years.

Common Sand Filter Problems

In this section, I will go over some troubleshooting for different sand filter issues.

Sand leaking into the pool water

It is not uncommon to find small amounts of filter media in the pool water with both DE and sand filters. When changing the sand or backwashing, you may notice bits of sand have made their way into the pool. This usually isn’t a problem as long as the amount of sand is minimal.

If you notice unusual amounts of sand collecting in the pool, there may be a more significant issue at play. Old filters may have worn down, or parts may be broken, so you will likely need to take the filter apart and examine all of the components.

Causes and solutions for sand leaks

The first step in fixing this issue is to determine the cause of your filter blowing out sand.

Overfilling sand

The most common reason sand leaks into the pool is overfilling the filter tank. It is important to learn the correct quantities when filling your sand filter or risk sand overflowing into your pool water. Read my guide on filling your sand filter for more info.

Broken lateral or standpipe

Another possible reason your sand filter leaks sand into the water is broken parts such as the lateral or standpipe. If your standpipe and/or lateral are broken, you will notice large amounts of sand leaking into the pool. To fix this, purchase new parts, remove all the sand from the filter tank, and replace the broken parts.

Damaged backwash valve

Your backwash valve may also be causing this problem. If there is a leak or issue with the sealing in the backwash valve, small amounts of sand could leak into the return pipe and make its way to the pool when you backwash. This is usually a relatively easy fix as you will only need to replace the O-ring for the valve. On the other hand, you will need to replace the entire valve with a more heavily damaged backwash valve.

High filter pressure

High filter pressure is something all pool owners will run into at some point, and it is not usually something to worry about. Depending on the specific sand filter model, you should expect to keep your filter pressure at 5-20 psi. Check the manufacturer’s instructions for the optimal range.

If your filter pressure goes too far over the recommended range, you risk a burst filter which can be very dangerous. This is why it is very important to stay on top of your filter maintenance.

Causes and solutions of high filter pressure

Here are some of the common causes of high filter pressure.

Dirty pool filter

The majority of the time, high filter pressure affecting your sand filter is due to a dirty filter. The filter pressure builds as the sand particles catch algae and other debris. This can be fixed by simply cleaning out your filter and backwashing.

Air leak

If the pressure in your sand filter is still too high after cleaning and backwashed the system, you may be dealing with an air leak somewhere in your filtration system or pump.

If this is the issue, it is a bit more tedious to fix, but it is still possible to do it yourself. Signs of air leaks in your filter are bubbles coming out of your return line or in the strainer pot of your filter system.

There are several ways to fix an air leak, but it usually involves filling the pool water more, replacing a damaged O-ring, or replacing old broken plumbing components. Contact a pool professional for assistance if you cannot fix the issue yourself.

Clogged return pipe

The final cause for high filter pressure is clogged return pipes. Due to the constant flow of debris from the pool water into the pool filter, your plumbing can eventually become clogged. If this happens, less water will be able to escape the filter, and the pressure inside will build up.

Fixing this issue likely involves taking the filter apart. It may be possible to unclog the pipes by placing a hose in the piping and pushing high-pressure water into the clogged area. But more likely than not, you will need to take apart the system to unclog it.

Low filter pressure

Low filter pressure is less common and less dangerous than high filter pressure. But that doesn’t mean it isn’t important to fix it. Low filter pressure means water is not flowing through your filter at an acceptable rate, so the pool water is not getting cleaned properly.

Causes and solutions of low filter pressure

Here are some common causes of low filter pressure.

Clogged skimmer basket

The most common reason for lower filter pressure is a full skimmer basket. If you notice your filter pressure is low even after the pool pump is turned on, check your skimmer basket. If the skimmer is full of debris, empty it, and you will likely see the filter pressure return to normal.

Clog in the plumbing before the filter

If the skimmer basket is empty, but the filter pressure is still well below average, your culprit is likely a clog in the plumbing. For the pressure to be low, the clog will have to be before the filtration system. You will likely need to take apart the plumbing to clear any blockages to fix this.

How to Know It’s Time to Replace Your Sand Filter System

Sand filter systems can last a very long time if maintained properly. But, inevitably, they will eventually need to be replaced. You should expect your sand filter to last 2-3 decades if you keep a consistent cleaning schedule. Over time, your tank, plumbing, and pump will start to collect mineral deposits and wear down. Individual parts can be replaced, but there comes a time when there is nothing you can do but purchase a new filter altogether.

There is no rule for when you will need to purchase an entire new pool filter system. The choice is really up to you to weigh the pros and cons and the cost benefits of investing in a new system. If you feel like you need a new system, check out my recommendations for the best pool filter.

Sand Pool Filter Maintenance Tips to Keep It Running Well

Here are some final tips and tricks for keeping your sand pool filter running optimally.

Change your sand when needed

Many pool owners sleep on this, but it is extremely important to change your filter sand every 3-5 years, or when the filter sand is showing signs that it is no longer effective. Some common signs that your pool’s filter sand needs to be changed are:

  • It has been 3-5 years since you changed the pool sand
  • Cloudy, dirty pool water
  • Clusters of sand forming in your filter
  • Water creating channels in the sand

You can read my guide on how to change your pool filter sand to learn how to do it.

Backwash and clean your filter consistently

I recommend that you backwash your sand filter at least every 2 weeks. However, on top of that, you should also deep clean the filter 2-3 times a year. For this, I usually drain the filter and thoroughly rinse the sand and filter tank until the water comes out clear. Sometimes, simply backwashing isn’t enough, and this is necessary to prolong the life of your filter sand.

Don’t skimp on the sand

There are hundreds of pool sand products on the market, so I can understand how overwhelming it can be to choose one that works best for your system. Talk to a pool professional at your local pool store to get advice on the best sand for your specific system. But in general, I highly recommend purchasing silica sand. It is the best performing, longest-lasting, and most efficient option on the market. It costs more than other products, but you get what you pay for.

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Bottom Line

Sand pool filters can run into a few problems during their lifetime, but they are pretty easy to troubleshoot and fix most of the time if you know what to look for. Check out my guide with more troubleshooting tips for every type of filter if your pool filter is still not working.

Have questions? Let me know.

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