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If you have sand in your pool and operate a sand filtration system, you know immediately where the sand comes from.

If you don’t have a sand filtration system (and don’t live on the beach), then what you think is sand is probably not sand at all. More likely, you are dealing with the yellow mustard algae.

Test to see if it is mustard algae by scrubbing the areas with a pool brush. If a cloud forms, you have mustard algae in the pool, if not, it is actually sand.

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How does sand get into the pool?

If we exclude the pool near the beach, sand storms and other experiments, the sand filter is the only cause of sand in the pool, but what is the problem?

We must first understand how a sand filter system is constructed.

In a salt filter system, a large standpipe runs from the top to the bottom with what is called a filter bowl or filter star. Within it are fine fins that retain the silica sand and the impurities that are sucked out.

The reason for sand in the pool is either a crack in the standpipe or in one or more lamellas.

The standpipe is much thicker and stronger than the lamellas. The probability that the standpipe will crack is rather low. The chance is much higher that one (or more) of the side tubes (fins) is damaged. As a result, sand can enter the pool.

It is not easy to look inside the filter. Know exactly what happened, you will never find out. The most common causes are:

  1. With an old filter, the pipes just eventually give up the ghost and become more and more porous until eventually cracks form and sand gets into the pool.
  2. The sand filter system has been moved, the shifting of the weight may have cracked one or more of the pipes. Filter systems that have been in service for a long time are especially susceptible.

If you have done something to your sand filtration system recently and now have sand buildup in the pool, it may be due to something else.

Not every case of sand in the pool is due to damage to the internal piping of the sand filter. There may be other reasons for sand in the pool.

However, these other possible causes are always related to your behavior and are therefore easier to identify:

  • The wrong sand: sand filter systems rely on the use of certain quartz sand. The fins have defined openings, so smaller grits can allow the filter sand to get into the pool. Typically, sand filters are designed for sand grains with a diameter of 0.4 to 0.8 mm or from 0.7 to 1.25 mm. Furthermore, you should always use professional pool filter sand.
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  • Sand got into the pipe when refilling: Use a filling aid when refilling the filter system so that the sand does not get into the standpipe and thus is not flushed into the pool by the water.
  • Too much sand in the filter: Only add sand to the filter according to the manufacturer’s instructions. If there is too much sand in the filter, the excess sand can be stirred up during backwashing, get into the valve or the standpipe and then be carried by the water into the pool.
  • No clear rinse after backwashing: After a backwash, you must perform a final rinse (also called a clear rinse) to flush the sand back into the filter bowl.

You’ve now identified the problem, but how can you remove the sand from the pool and make sure no more comes back?

Repair a broken standpipe or side pipe

The problem is quickly identified, and the sand filter system is quickly identified as the cause. The difficulty is repairing it. To do this, you need to disassemble the sand filter, completely remove the sand, find the damaged part, replace it and then add new sand.

There is no need to hide anything here. The repair is time-consuming and not exactly pleasant. However, a professional is not needed for this project either. A free afternoon and some sweat is enough. The reward will be a swim in the sand-free pool.

How to remove sand from the pool

Once the filter is running properly again, it’s time for you to remove the sand from the pool. The broken filter may have provided quite a layer of sand in your pool. The fine grains of sand can be difficult for your filtration system to capture. Now it’s time for some manual labor.

Step #1: Use a pool brush to sweep up the sand.

Use a pool brush to sweep the sand in the pool into one area. This will make the next steps easier for you.

Note: Soft vinyl pools will be damaged by hard steel bristles. If you have a pool with vinyl walls, you should choose a pool brush with soft bristles such as nylon bristles.

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Step #2: Set the filter to waste

Turn off your pump, then change the valve from “Filter” to “Waste”. Water that is drawn in while in Waste mode is flushed directly out of the pool and does not enter the filter.

Pool water interspersed with sand grains is removed from the water circuit in this way. Operation in waste mode is quite expensive, because the water is lost. However, with the water, you also get rid of the sand and other impurities.

Tip: Overfill your pool before you start to make sure you always have enough water in the pool.

Step #3: Vacuum

Vacuum up the sand with a pool vacuum (or try a robotic pool cleaner). The filter set to “waste” is important to keep the mixture of sand and pool water from getting into the filter and getting caught in the side tubes.

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Tips:

  • Be careful when vacuuming not to stir up the sand, because then it will just settle back in other places.
  • Run your garden hose in parallel to keep enough pool water in the pool even while vacuuming.
  • Vacuum the sand as quickly as possible to avoid wasting water unnecessarily.

Conclusion

Repairing the sand filter system and removing the sand from the pool are not as difficult as they first seem. As always, the first step is the most important. With our instructions and tips, you will be well-equipped to do it – and without any professional help at all.

Larry has been a true water rat since childhood. Pure pleasure turned into a passion. That's why he is the first point of contact for friends and acquaintances when it comes to pool-related problems. He is an integral part of the PoolHandbook editorial team.