Filter socks are one of the most basic forms of mechanical filtration for reef tanks. The basic idea is that your water will drain through them and the large debris will be pulled out before it moves through your sump or filtration. This way the particulates in your aquarium can be removed before they are broken down and turned into dissolved organic waste.

Filter socks come in few different styles.  Those with a rigid plastic ring on top are designed to 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.

The drawstring style filter socks work nice 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 need to be changed more frequently. The nylon mesh socks are a bit easier to clean but still will not catch as much debris.

You will also notice different Micron sizes available.  Micron is short for micrometers and are the unit used to measure the pore size in the socks.  The higher the micron, the larger the holes or pores in the material and visa versa.  The smaller holes on a 100 micron filter sock means that it will collect smaller particles and more of them compared to a larger 300 micron sock.  This means a smaller micron sock is more effective at filtering out particulates but will also clog up quicker.

Changing out your filter socks on a regular basis is very important for the health of your tank.  Letting the socks sit in your tank for too long gives the organic debris they have collected time to decompose, flooding your system with extra nitrates and phosphates.

Because these organics feed algae in your system and in elevated levels can harm your livestock, it is actually better to not to use filter socks at all rather than leaving in for extended amounts of time without being cleaned.

Everyone’s sock maintenance schedule will be slightly different depending on their individual systems, but 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.

Although it may seem easiest to just throw a filter sock away once its been used, cleaning and reusing them can save you quite a bit of money in the long run.

One technique to clean your socks is to turn them inside out and throw them in your washing machine.  Make sure that you are not using soap when washing them but you can use a couple capfulls of bleach.  I usually run the socks through a full cycle with hot water and then run an additional rinse cycle thereafter to get them extra clean and rinse off any bleach that may be leftover.

Another technique is to fill a bucket with hot water and add some bleach.  Then let the socks sit in the bleach solution for a few hours or even overnight.  Once you take it out rinse the inside and outside until most of the debris has been removed.  Afterwards it is a good idea to soak the sock again in a mixture of water and Seachem Prime.  The Prime will neutralize any ammonia and will remove chlorine in the water.

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 pretty clean.

Because most of these cleaning techniques do take a bit of time, it is best to keep several socks on hand so that you put in new socks while the dirty ones are out of commission.  Personally, I keep about 10 filter socks on hand and throw the dirty socks in a bucket in the backyard; when I start to get low on clean socks I wash all of them out which usually ends up about once per month.