How to Clean Felt Filter Socks and Filter Bags & FAQ

How to Clean Felt Filter Socks and Filter Bags & FAQ

Aquarium Filter Socks dirty to clean

Felt Filter Socks

The Aquatic Experts Way to Clean

Many people have asked us about the best way to clean their filter socks.  Some people will take their aquarium filter socks and simply clean them at a sink. While this may work for thin mesh bags, fine micron felt filter bags require a more thorough cleaning process to remove trapped particles.

When you remove your filter socks for cleaning, ensure that they are empty by shaking them out into a bucket.

Depending on how your aquarium overflow system is built, it is possible to find all sorts of critters including small fish, crabs, snails, bristle worms, sea cucumbers, as well as algae, pieces of rock and other mysterious materials.

Many times trapped animals will actually be alive and can be returned to your aquarium. Since our method uses a washing machine, it may be more efficient to collect several sets of dirty socks [from previous changes] before cleaning them.

How to Wash your Aquarium Filter Socks

  • Optional - run your washer in a hot rinse cycle to remove all soap residue (normally only necessary in older machines).
  • Set washer to heavy-duty cycle and wash socks in hot water. (Note: any temperature seems to give good results with this method.)
  • Use 3 capfuls (teaspoons) dye- and fragrance-free bleach (Sodium hypochlorite with no additives).
  • DO NOT Use OxiClean, laundry detergent, or any other soap product.
  • Add an extra rinse cycle at the end of the wash to ensure the bleach is removed.
  • After you remove socks from the washer they may still have a hint of bleach smell.

How to Dry your Filter Socks

  • Place socks in a clean, chemical free open air environment to dry for at least 48 hours.
  • Should you need socks sooner - place them in a bucket with 2 gallons of water with 1/5 teaspoon of Aquatic Experts Premium Complete Water Conditioner or similar chlorine remover for 30 minutes.


  • Filter socks can be dried in a clothes dryer but USE LOW HEAT ONLY! Obviously no fabric softeners or anything else.


  • Thoroughly rinse new filter socks with clean fresh water, wring them out and repeat this process before using them in your filter. You can also follow the above method and clean new socks in the washing machine.

New filter socks may have a non-toxic residue from the manufacturing process which can cause bubbles throughout an aquarium and make protein skimmers overflow for several days. After a few days the skimmer will go return to normal. This phenomenon can be avoided by rinsing filter socks well before use.

  • If you have any residual fishy smell in your washing machine after you remove the socks you can always run a quick wash with bleach in an empty washer.  If there is any odor in your aquarium, you can use activated carbon in our fine drawstring mesh bags to eliminate the smell, along with any discoloration in your tank.


Q. How do you know when to change filter socks?

A. No two aquariums are alike; each is stocked with different types of livestock of various sizes and quantities. Add these diversities to the various amounts and types of food each aquarist uses and you see there are many things that impact how often filter socks need to be changed. With that said, a simple means for determining the optimal time to change filter socks is to watch as the water level in the socks rises. As filter socks trap debris, the pores get clogged and the water level inside the sock rises. The increased water level indicates the increase in waste collected. The more often you change filter socks, the better the water quality. This is especially important for aquariums such as living reefs which require low levels of nitrates and other nutrients.  

Q. When you remove dirty filter socks from the sump, do you just let them dry out until it's time to wash them?

A. Since we always use bleach I have not noticed any difference between cleaned dry socks or wet socks. With my service company we have an open bucket to keep dirty socks - some are dry others are wet. Personally, I collect my socks in a fish safe bucket for weeks sometimes months. They are all dry except the most recently changed filter socks which are wet. You can also put dirty socks from an aquarium directly into a trash bag and tie them off. When the collection of trash bags is large enough to suit your needs, open and dump the dirty socks into the washing machine. This method works well and traps any unpleasant odor. Dry or wet, when you follow our cleaning directions on this page you will have success.

Q. When should you throw away your filter socks?

A. Quality filter socks should last through many cleanings in a washing machine. Eventually you will see holes, stitching will come undone or a glue joint will separate; at this point you will know it is time to replace your filter socks.  

NOTE:  Some filter sock manufacturers purposely continue the stitching off one corner of their filter socks. Please do not cut these threads; your filter socks will last much longer.



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