Improving Sand Pool Filtration

Sand pool filters need some help from time to time. If your sand filter seems to be limping along, just barely keeping its head above water, this post is for you.

Sure you could buy a new large and shiny filter, and all your pool water problems will be over - but if you want to save a few bucks... there are ways to improve your filtration.

DE Powder

  • Diatomaceous Earth, used in D.E. pool filters, can also be used in sand filters and cartridge filters to trap particles down to 3 microns in size. Use 1-3 cups depending on your filter size, by pouring it into the skimmer after backwashing, and it forms a layer on top of and down into your sand bed. Also useful, and some say better to use is Aqua-Perl, a volcanic mineral filter aid used as a substitute for DE powder.


  • Clarifiers are very popular and easy to use. Just add a few ounces per week, and the polymer seeks out and sticks to dirt and contaminants, and then attracts more, until the particle size gets big enough so your filter can remove it from the water. Gel clarifiers, sold in packets, are especially useful with sand filters (and not recommended for DE or Cartridge).


  • Aluminum Sulfate, known as Alum can be used as a pool flocculent, broadcasted over the pool surface, for extreme cloudy pools. It can also be used as a filter aid, by pouring 1-2 cups into the skimmer after backwashing. It forms a jelly-type layer on the surface of the sand bed, acting like another filter, as it traps the dirt entering the filter. Make sure to only use Pool formula, not Garden formula Alum.

Slime Bag

  • What'd you call Me? The Slime Bag is a product that attaches to your pool return and acts as a secondary filter. It's great for sand filters that spew a stream of visibly dirty water back into the pool while vacuuming. It can also be used more often than just during vacuuming, to trap small particles, down to 2 microns.

Filter cleaner

  • Keeping your sand bed clean may require an annual cleaning with a sand filter cleaner that will remove both greasy oils and flaky minerals. I like to use Filter Perfect, or our Sand Cleaner is good too. Instead of using products to compensate for your lousy filter, you can actually make your filter less lousy! Using a filter cleaner rejuvenates filter sand.

Sand Alternatives

  • An easy way to improve the effectiveness of a sand filter is to put in something other than regular pool filter sand. Alternatives exist, America! You can use zeolite minerals with ZeoSand. Both of these will outperform regular sand by filtering to a smaller particle size.

Thanks for stopping by, I wish you well on your journey to better pool filtration this summer! One more tip - do not backwash your sand filter too often, they actually work better when they are a little dirty. Wait until the pressure gauge rises 7-9 lbs before backwashing.

In The Swim makes every effort to provide accurate recommendations based upon current ANSI/APSP/ICC-5 2011 (R2022) standards, but codes and regulations change, and In The Swim assumes no liability for any omissions or errors in this article or the outcome of any project. You must always exercise reasonable caution, carefully read the label on all products, follow all product directions, follow any current codes and regulations that may apply, and consult with a licensed professional if in doubt about any procedures. In The Swim assumes no legal responsibility for your reliance or interpretation of the data contained herein, and makes no representations or warranties of any kind concerning the quality, safety, or suitability of the information, whether express or implied, including, without limitation, any implied warranties of merchantability or fitness for a particular purpose.