6 Common Sand Filter Problems

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Since the dawn of civilization, humans have used sand to filter water. Ancient Egyptians, Indians and Greeks all knew this trick: the fine grains of sand beautifully sift out even tiny pieces of debris and allow clean water to flow through. Even in our modern age, sand is still one of the most effective and low-maintenance ways to filter pool water. Famously low maintenance and easy to clean, pool sand filters are very effective and, for the most part, a pleasure to own.

No filter is perfect, though. Over time and use, they can develop issues. Learn how to spot these quickly, and fix them before they cause bigger problems.

1. Old Sand in the Filter

As strange as it sounds, the sand in your filter can wear out over time. The edges get worn down and this leaves gaps that can allow debris to get through, which makes the filter much less effective. If you notice that your pool water looks cloudy, you might need to replace either the sand in the filter or the filter itself. It's a common rule of thumb to replace the sand in a filter once every seven years, though this varies depending on use.

2. Broken Lateral Lines

If you are seeing sand in your pool or around the filter area, one of the lateral pipes may be cracked or broken. The lateral lines are designed to allow water, but not sand, to pass through them. If you start to see sand in the water or around this area, check the laterals for any signs of cracking. The broken areas of these pipes must be patched or replaced.

A sand filter system with blue pipes

3. Gunk

Tiny deposits of oils from human hair and skin can build up over time. If you leave this problem unchecked, eventually your filter will be almost completely ineffective. Make it a habit to treat your system with a liquid sand filter cleaner at least once a year. These products are available at most pool stores.

4. Dirt in the Filter

If your water has visible debris in it, check the filter for dirt. You can also look at the reading on the pressure gauge. If you can see dirt in the filter or the gauge reads eight to 10 pounds above clean levels, it's time to backwash your filter. This means you will flush water through the filter in the opposite direction. The process will release trapped dirt and send it out through the waste line. Use the multiport valve or the push-pull valve to reverse the flow of water through the sand filter and backwash it.

5. The Wrong Sand

The sand in your filter must be the right size. Sand comes in multiple grain sizes, so you can't grab any sand and put it in the filter. You generally want 20-grade silica sand that is 45 to 55 mm in diameter. However, check your filter manufacturer's information to get the correct sand measurements.

Adding sand to a pool filter

6. The Wrong Size Filter

The filter should take only 6 to 8 hours to completely clean the pool. If your filter takes much longer, you're using an undersized filter. Always be sure to read the manufacturer instructions and note the recommended pool sizes before you buy. On the other hand, if your filter is working only in very short cycles, you may have too much water flowing too quickly through the filter. Check the flow rate against the recommended flow rate settings for your filter and make adjustments as needed.

Address your sand filter's problems as soon as you notice them, and it will keep your pool water clean and beautiful for ages to come.