How Sand Filters Work In Swimming Pools

In our next installment of prepping your swimming pool for the upcoming season, we are going to discuss the third type of filter you can have for your swimming pool, a sand filter. This is by far one of the most popular filters used to keep swimming pools clean and a filter that is very easy to operate.

Sand filters are simple to use, require the least amount of maintenance and for the most part, do a great job at keeping your swimming pool clean, blue, and clear! As far as price, they are usually the least expensive filter you can buy and this is why it is the first choice for many when they need to pick out a filter for their swimming pool. With this blog post, we would like to highlight the benefits of a sand filter, how to backwash them, and what to look for when the filter needs to be replaced.

How Do Sand Filters Work?

As the water flows down through the bed of sand, dirt and debris get trapped.  When the clean water exits through the bottom of the filter, it is then returned to the pool through lateral tubes which are located at the base of the filter. As far as the three filters we have discussed,  sand filters debris down to approximately 20 microns and anything smaller probably will not get filtered out. Sand filters don’t filter down as much as DE and Cartridge.  This is why if you have a plaster pool with very little vegetation (trees, bushes, leaves etc.) in the backyard a sand filter will work just fine for you. However, the more vegetation you have along with Pebble Tec pools we recommend cartridge (great for water conservation) or DE filters for higher levels of filtration needed.

How Do You Backwash Sand Filters?

  1. First, attach a long enough backwash collapse-able hose or PVC pipe to the waste or backwash port of your sand filter. You will want to make sure they are long enough to divert water away from where you are.
  2. Turn your filter system off and switch the valve to the “backwash” position. This can either be located on the top or side of the filter.
  3. Turn your filter back on and let the water rush out of the backwash port and through the backwash hose for approximately 1 – 2 mins or until the water runs clear.
  4. When it is finished turn your pool filter system off and turn the handle back to the regular filter position.
  5. Turn your filter back on and rinse your filter for about 30 seconds.
  6. If your swimming pool hasn’t been back washed for a while, you can repeat steps 2-5 again until the water is clear.

Typically, you will want to backwash your swimming pool when the pressure gauge gets to 7-10 PSI above the starting point or when the needle reaches the “dirty” position.

When Should You Replace The Sand In Your Filter?

The following are reasons why the sand in your filter might need to be replaced:

  1. The pool isn’t staying clear
  2. The filter continues to run at high pressure even after backwashing
  3. When you open up the filter check to see if channeling has occurred or if the sand is clumpy
  4. If you see sand on the bottom of the pool (this usually means a cracked lateral)

On average, the sand will usually last 5 – 7 years! If you should have any questions about any of the filters we have discussed, please contact us today!