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Swimming Pool Filter Maintenance Tips

The filter is the true workhorse of any swimming pool – it keeps your water circulating, removes dirt and debris, and generally keeps your pool looking great. But your filter can’t do the job alone. To keep pool filtration systems running at peak performance, the right maintenance routine is critical.

Not sure where to begin? New to the world of inground pool filters and swimming pool maintenance? No worries. In this article, we’ll look at the three main types of pool filters – sand filters, cartridge filters, and diatomaceous earth (DE) filters -- and give you the dirt on how to keep them going strong for years to come.

Sand Filters

Sand filters are an affordable and popular choice for both above ground and inground swimming pools. Water goes into the filter and passes through a thick layer of special pool-grade sand. The sand traps dirt and debris, and the clean, clear water flows back into the pool.

How to clean your pool sand filter: Eventually, all of the dirt and debris from your pool water will build up in your sand filter and cause it to work less efficiently. And when that happens, it’s time to backwash. Backwashing is a pretty simple process: All you have to do flip a switch and reverse the water flow. How do you know when to backwash? That’s easy, too: All sand filters have a pressure gauge. You’ll need to backwash when the filter pressure gauge reads seven to 10 pounds over normal operating pressure.

Sand filters actually work better when there’s a bit of dirt and debris present, so you actually don’t want to clean your sand filter too often. Your backwashing schedule will vary depending on factors like the size of your pool and how often you use it, but if you aim for once a week (or even every other week), you should be in the clear.

Pro tip:

In addition to backwashing your sand filter regularly, you should also use a specially formulated filter cleaner at least once a year. You should completely replace the sand once every five to seven years.

Cartridge Filters

As the name suggests, these filters use removable cartridges to capture impurities in your pool water. Cartridge filters have more surface area than sand filters, which means they are less prone to clogs than sand filters. They also operate at a lower pressure than sand filters, which means they’re a bit more efficient, too. Of course, you’ll pay a bit more up front for a cartridge filter – but you’ll also spend less time (and less money) on maintenance, so the tradeoff might be worth it.

How to maintain a cartridge filter: If you’re looking for ultra-low maintenance, it doesn’t get much easier than this: All you have to do is pop the cartridge out and rinse it off with a garden hose (for a deeper cleaning, you can also soak it in mild detergent).

For best results, you should rinse off your filter every two to six weeks, depending on the size of your pool and how often you use it. Plan to completely replace the cartridges every three to five years.

Swimming Pool Filter

Pro tip:

Make sure to turn off the pool pump before you start the cleaning process!

Diatomaceous Earth (DE) Filters

DE filters are similar to sand filters: Both filters use a fine, granular filter media. Both filters have pressure gauges, and they both require backwashing when the pressure gets too high. There are two key differences, though:

  • DE filters only need to be backwashed a few times a year (compared to weekly with sand filters)
  • You’ll need to add new DE every time you backwash your filter (rather than replacing it every 5 years or so)

Cleaning Your Pool With . . . Fossils?

Diatomaceous earth might look like sand, but it’s actually a powder made from the crushed, fossilized diatoms, which are a type of algae with a hard, shell-like exoskeleton.

How to maintain a DE filter: To keep your DE filter in good working order, do a deep cleaning at least once a year. Disassemble your filter and clean the grid with filter cleaner – and while you’re at it, check for damage or wear.

Pro tip:

Keep an extra bag (or two) of DE on hand. That way, you’ll have it ready when it’s time to backwash.

Filter Maintenance FAQs

Q: Which swimming pool filter is best for me?

A: There are pros and cons to every type of pool filter. Sand filters are inexpensive to purchase but require more frequent backwashing. DE filters are pricy, but they’re super-efficient. Cartridge filters are a great choice if you want your pool to be as low-maintenance as possible.

Q: How often do you need to clean a pool filter?

A: Proper pool filter maintenance depends on several factors, including the type of filter you have, the size of your pool, and how often your pool is used. In general, though, here’s what to expect:

  • Sand filters need to be backwashed once a week. Sand needs to be completely replaced every five years or so.
  • For cartridge filters: Clean the filter every two to six weeks and replace cartridges once every two to three years.
  • If you’ve got a DE filter, you’ll need to backwash it and add new filter media a few times a year.

Q: What should I use to clean my pool filter?

A: Gentle dish detergent works well on pool filters. You can also buy specially formulated filter cleaning solutions. You can even buy complete pool care kits that include everything you need for pool maintenance, from filter cleaner to chemicals to testing kits – check with any store that sells pool supplies.

Q: How long do I backwash my sand pool filter?

A: Every filter is a little different, so we recommend checking the instruction manual or talking to your pool professional about sand filter maintenance. In general, though, it should take two to three minutes. Most sand filters have something called a “sight glass” near the backwash valve that allows you to see the water as it goes from cloudy to clear.

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