Changing Your Pool Filter Media

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Pool filter media is just a fancy term for the stuff inside your pool filter tank - the material that traps the dirt. Now you know that I'm speaking of pool filter sand, filter cartridges, or grids - if you have a D.E. pool filter. This post will tell you how to change your pool filter sand, cartridge or D.E. filter grids. Now that we have established "What" it is, let's talk about Why & When - before we move onto "How" to change your pool filter media.

Why Replace Your Pool Filter Media?

Filter Sand: Over time, your pool filter sand will deteriorate. Filter sand loses it's sharp edges, and the sand grains become rounded. When this happens, the grains don't lay flat against each other, and it becomes (on a very small scale) like trying to filter through a vessel full of ping pong balls. Filter sand also can trap grease and oils deep in the sand bed, which won't always backwash out of the filter. In hard water parts of the country, with very high Calcium Hardness levels, filter sand can calcify, or become hard like sand stone.

Filter Cartridges: Pool filter cartridges are made of a woven polyester, with very small gaps between the nearly microscopic fibers. These fibers trap the dirt and contaminants. When cleaning your filter cartridge, the fibers stretch and separate, and over time portions of the cartridge allow dirt to pass through unfiltered, while other areas will reduce water flow and necessitate more frequent cartridge cleaning. Each time you clean your cartridge, it loses a little bit more of it's filtration ability.

DE Filter Grids: The fabric that stretches over the plastic frame can develop holes, and the stitching unravels as time goes by. This will allow the DE powder to pass into the pool, reducing filter effectiveness. Another issue occurs when oils and minerals clog the pores of the fabric, raising the filter pressure and reducing flow rate, also reducing filter effectiveness.

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A thorough cleaning of any filter media type with a Filter Cleaner product, to remove oils and minerals will extend the life of all filter media types, and may be a good idea before replacing your filter media, at a much higher cost. But it can't be used forever; eventually the material (your filter media) will become so compromised that using a Filter Cleaner will yield diminishing returns.

Another good reason for replacing your filter media is that when your media becomes "tired", you will need to run the pump longer and use more sanitizer to maintain water clarity. Not to mention the expensive-to-correct water problems that may result. It's costing you more money than you think to have poor pool filtration.

When Should You Replace Pool Filter Media?

It's difficult to state an accurate number of years - for when you should change your filter media. This is because not all filters are sized properly for the pool size. If your pool filter is extremely undersized, you may need to change it every year. However, assuming proper sizing, "they say" that filter sand will last 7-8 years, filter cartridges 3-4 years and DE grids should last around 10 years.

The best determinant to when you need to change your pool filter mediais when you notice that you need to run the pump longer or use more chemicals to maintain water clarity. Or, you may be having more trouble with algae or cloudy pool water than you did in previous years.

The amount of time between backwashing, or cartridge cleaning can also be used as a gauge. When you are having to backwash the filter twice as much as you did before, you can rightly assume that your filter media has half the dirt-holding capacity that it once had.

How to Change Your Pool Filter Media

Filter Sand Replacement:

  • Shut the pump off, remove the filter drain plug. Drain overnight.
  • Remove the top-mounted Valve or Dome on top of the filter tank.
  • A wet/dry vac can be used to suck the sand out, or use a plastic cup.
  • Use care at the tank bottom to avoid damaging the laterals.
  • Pour in the required amount of #20 Silica Sand.
  • Replace multiport Valve or Dome securely. Replace drain plug.
  • Start up filter on rinse or backwash, to flush out the sand dust.

Filter Cartridge Replacement: This one is fairly easy - just order the correct replacement cartridge(s), open the filter tank and insert cartridge. You can order the correct cartridge by the printed part number on the end-cap, or by filter manufacturer, or by the length and width dimension.

The bottom of the cartridge should push onto a fitting at the bottom of the tank. Some models also have a piece that inserts on the top of the cartridge(s), before securing the filter lid.

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DE Filter Grids ReplacementYou can replace just one or two grids, but if they have some age to them, it may be wise to replace the entire DE grid set (7 large, 1 small).

  • Backwash filter thoroughly.
  • Shut off pump, open air bleeder and remove drain plug.
  • Remove belly band clamp and pull off tank upper half.
  • Grab the top manifold and wiggle / lift the grids out of the tank.
  • Use a garden hose to hose off extra D.E. powder still on or between grids.
  • Loosen the wing nuts on the manifold, and wiggle/pull the manifold off.
  • Discard the old grids, reassemble in the same fashion with new grids.
  • Adjust the spacing of the grids with the assistance of the bottom spreader plate.
  • Tighten up wing-nuts on the manifold, to pull the assembly together tightly.
  • Reinstall the grid assembly into the tank and replace the filter lid and drain plug.
  • Reinstall the clamp band, tightening until all spring sides touch each other.
  • Open all valves, open air bleeder, then restart filter pump, watching for a gauge spike.
  • Add DE powder through the skimmer, at a rate of 1lb per 5 sq. ft. of filter surface area.


So, that's it - the What, Why and How of pool filter media replacement. Not so complicated, now is it? You may still have some doubts about whether you can take on this job yourself. If so, feel free to give us a call with your questions on how and what to replace. Any of our pool filter experts will be able to help get your pool filter in top shape again.


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.