How Often Should I Change the Sand in my Pool Filter?

Even if you have a good pool maintenance routine, there are still some pool maintenance tasks that seem to get neglected. These tend to be the tasks that only need to be done every few years. One of those tasks is replacing the filter sand. How often should you replace the sand in your pool filter?

Ideally, you should change the sand in your swimming pool filter every 5 years. You may need to change your sand sooner if you notice that your filter is not cleaning the water effectively anymore and you find that you are having to backwash your filter more often than normal.

The larger your filter and smaller your pool, the less often you will need to replace your sand, but the rule of thumb is generally 5 years. If you run your filter at the absolute minimum, you may find that your sand can last you as long as seven years.

You may need to replace your sand earlier than 5 years if you experience certain problems with your filtration system. Let’s look at the scenarios where you will need to replace your filter sand and what causes them.

How Do I Know If My Sand in my Filter Needs to be Changed?

While the rule of thumb is to change your filter sand every 5 years, there are certain problems that can arise earlier and can only be fixed by replacing the sand.

  1. If there is little to no suction in the skimmer, the pressure is too high or the pump is straining despite constant backwashing.
  2. The filter is not cleaning the water efficiently, but the suction, pressure, and pump are all running fine.

1. If there is little to no section in the skimmer, the pressure is high and the pump is straining.
You may start to notice that you are having to backwash your filter more and more often, and despite backwashing, the pressure in your filter only drops temporarily before increasing again putting a strain on your pump. You may also notice there is little to no suction in the skimmer. If this is the case, it is very likely that your sand has gone bad and needs to be changed.

  • Sand can calcify from water with high calcium hardness
  • Sand can start to mudball, forming clumps of greasy sand
  • or, the sand is just so completely saturated with debris to the point that backwashing alone can’t remove it.

2. The filter is not cleaning the water, but the suction, pressure, and pump are running fine and the water is constantly cloudy.
If the suction in your skimmer is still fine and the filter pressure is good, but the filter is not cleaning the water effectively, then your sand level is most likely low or the sand is worn out and needs to be replaced.

  • Sand can be worn out over time. Filter sand is meant to be rough, and these microscopic sharp edges are what traps dirt and debris. After a few years of use, the sand grains start to wear down from rubbing against each other, making them smooth. Similar to how rocks become smooth pebbles over many years of being washed around. Once these grains of sand are smooth, they can no longer trap dirt efficiently.
  • After many years of backwashing, the sand level in your filter will start to run low. When you run your filter on backwash, the water runs through the filter in reverse, washing up all the dirt in the sand. It is normal for some of the sand to wash out along with this dirt during the backwash cycle. After a few years, your sand level will be to low to filter effectively and you need to replace the sand.

How To Change the Sand in my Pool Filter?

So you have determined that your filter sand needs replacing. I want to walk you through the process step by step and save you from some common mistakes.

  1. Visit a pool supply store and purchase the correct amount of sand for your specific filter. The size of your filter will be marked on the side of the filter housing. Also, buy a new O-ring for the filter cover, the old one will be brittle and may start leaking soon. Backwash the filter properly (do not rinse) before going to the next step. This will loosen the sand and make it easier to remove.
  2. Remove the lid on the filter housing. Make sure you replace the screws in the threaded holes to prevent sand from blocking them up while you empty the filter.
  3. When you remove the lid, you will notice a vertical pipe running down the center of the filter. Cover the opening of that pipe using a plastic bag and some electrical tape. You do not want to get sand in there.
  4. Time to remove the sand. You should only use your hands and carefully remove the sand. Be gentle to avoid damaging one of the many “fingers” of pipes inside the filter. Never use a spade or similar tool to do this. There are sand extracting tools available for this job, ask your pool supply store if they have them available. Keep adding water while you are removing the sand to make this easier.
  5. Before adding the new sand, give the inside of the filter a good scrub. Now do not simply dump all the sand into the filter. First, fill the filter about halfway with water, then carefully add small amounts and evenly spread the sand around all the “finger” pipes at the bottom of the filter. Once you have covered the fingers with sand, it is safe to dump the rest of the sand in. When you are done the filter should be about 75% full of sand.
  6. Now remove the plastic bag from the center pipe. Give the outside of the opening a good rinse and replace the old O-ring with the new one. Now replace the cover and only hand tighten the screws using a screwdriver to prevent stripping the threads.
  7. Now backwash your filter for a full 3 minutes, then rinse it for 30 seconds. Then set your multi-port valve to filtration and you are done.

Don’t let the task of replacing the sand in your filter scare you off. If you follow these instructions carefully you shouldn’t have any problems. It really is a simple task, so there’s no need to shy away from it.

Changing your filter sand on time will prolong the lifespan of your pool pump and make it much easier to keep your pool clear and sanitized.

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