How To Clean Filter Socks

Filter socks are one of the most basic yet effective forms of mechanical filtration for reef tanks. The water that exits your tank through the overflow pipes goes directly into a filter sock that filters out particulates before the water moves through the remainder of your filtration. Filter socks are generally the first filtration the water comes in contact with after exiting your aquarium. They are a type of mechanical filtration that removes larger particles of waste and leftover food so it doesn't settle and break down in the aquarium. 

As filter socks clog up, it is important to remove and clean them to effectively export waste from the aquarium. It is recommended that you remove clogged-up filter socks and replace them every 3-5 days, more often if necessary. That means you're going to go through filter socks quite quickly so we always recommend having at least 3-4 socks on hand at all times. The good news, filter socks can be cleaned and reused!

Leaving a clogged filter sock in your aquarium is worse than not using one at all. The concentrated waste will begin to break down and ultimately release nitrate and phosphate into the aquarium water. 

Cleaning Filter Socks

Types Of Filter Socks

Filter socks come in a few different styles. Those with a rigid plastic ring on top are designed to be set inside a filter sock holder which is commonplace on most sumps and even some all-in-one aquariums.  The standard sizes are 4” and 7” diameter socks with the larger socks intended to handle higher flow rates on larger aquariums. Some manufacturers stray from the 4" and 7" standard socks and make custom filter socks, like the rectangular socks made by Eshopps.  

The drawstring-style filter socks work nicely if you do not have a filter sock holder, you can simply tie the sock onto the end of a tube or pipe in order to filter the water.

You will see filter socks available in both a fine-felt material and a nylon mesh. Fine Felt filter socks will pull more debris out of the water than their mesh counterparts but will also clog up and need to be changed more frequently. The nylon mesh socks are a bit easier to clean but will not catch as much debris.

Filter socks also come in different micron sizes which refers to the porosity of the material. The smaller the micron rating, the smaller the pore size in the material.  A 100-micron sock will collect smaller particles of debris compared to a 200-micron filter sock which also means the smaller-micron sock will clog up faster. 

Cleaning Filter Socks

How To Clean Filter Socks

Everyone’s sock exchange and maintenance schedule will be slightly different depending on their individual systems and how much waste they are dealing with.  A good rule would be to change or clean them every 3-5 days, or as soon as they get discolored. Keeping on this schedule will help to ensure that your filter socks are removing the organics from your tank rather than just storing them.

The best approach is to keep at least 3-4 filter socks on hand at all times, many of us end up with a dozen or more.  This way you always have a clean filter sock available and you can then wash the dirty socks in batches.  When it comes to cleaning your filter socks, there are a few different routes you can take. 

1. Washing Machine

The most efficient technique to clean your socks is to turn them inside out and throw them in your washing machine.

  1. Run a hot rinse cycle without the socks first, this will rinse away any detergent and soap from the washing machine
  2. Toss in the socks and run a heavy-duty cycle with hot water. Use 2-3 capfuls of fragrance-free bleach. NO SOAP OR DETERGENT!
  3. Once complete, you can remove the socks and let them air dry for at least 2 full days before using them.  Any residual chlorine will evaporate as the socks dry out. 
  4. If you smell residual bleach or need to use them before they can dry completely, soak them in a bucket of fresh water and water conditioner for a few hours to neutralize any bleach. Any dechlorinating water conditioner for aquariums will neutralize household chlorine bleach. 

2. The Bucket Soak

Fill a bucket with hot fresh water and add 1-2 capfuls (per gallon of freshwater) of fragrance-free bleach. Then let the socks soak in the bleach solution for a few hours or even overnight. After soaking, remove the socks and rinse the socks inside and out with a hose or under the faucet. It's not a bad idea to soak in a bucket of fresh RO/DI water and water conditioner thereafter to neutralize the bleach then do one more quick rinse before using in your aquarium. You cal always let the socks air dry before too because chlorine will naturally evaporate from the water as the socks dry out. 

Cleaning Filter Socks

3. Power Washer

Perhaps the quickest way to clean out your filter socks is with the use of a power washer or high-pressure water hose. With this method, all you really need to do is blast the socks until they appear to be clean. Be sure to turn them inside out and rinse both the inside and out. Let them dry before use. Just be careful of the water pressure, some high-powered washers can tear the fibers of your socks.  


1. When removing dirty socks, let them air dry outside before tossing them into an old laundry basket. Once every few weeks, you can then wash all of the dirty socks in a single batch. Letting the dirty sock air dry before going into an old laundry basket will help reduce or eliminate the smell so long as you wash all the socks at least every few weeks. This will save water, eliminate the hassle of having to constantly clean socks, and you won't have to deal with a smelly bucket of wet, dirty filter socks.

2. Always rinse NEW filter socks before use in your tank to wash away manufacturing residue. You can use RO/DI water but tap water is probably fine as long as you let it dry before using it. If you forget to rinse a brand-new filter sock, it will likely cause your protein skimmer to overflow because of the manufacturing residue on the filter material.  Should that happen, turn off your skimmer, run a fresh batch of carbon and do a water change.  24-48 hours later you can resume skimmer operation.