What does a filter sock do?

A filter sock is a type of mechanical filter and removes undissolved particulates from the aquarium water. Fish poop, leftover foods, organic debris, sand, etc.

Do filter socks remove nitrates?

No, a filter sock will not remove nitrate directly. They do, however, remove the organic debris and waste that breaks down and releases nitrate so it will slow down the rate at which nitrates are created in your tank.

Can I wash a filter sock?

Yes, filter socks should be washed and reused. The best approach is to have at least 3-5 filter socks on hand at all times.  When you remove a dirty one, you will always have a clean one ready for replacement. You can then wash them in batches and never be stuck without a clean filter sock on hand.

There are a few ways to wash a sock. Turning the sock inside out before rinsing with the hose or faucet works. The best approach, however, is to just toss them into the washing machine. DO NOT USE SOAP of any kind, run a quick wash cycle and then place them into a bucket. Fill the bucket with RO water for an extra rinse. Let them air dry and they are ready for use in your tank.

Are mesh or felt filter socks better?

Felt filter socks are thicker and will remove more debris.  his means they also clog much quicker and are more difficult to clean.  Mesh filter socks are thinner, won't clog as fast, and are a bit easier to clean but they just won't provide the level of clarity and filtration as a felt filter sock.

Most hobbyists use a felt socks just because they are more effective in terms of waste removal. Mesh socks can work great in situations where nutrient levels are not as much of a threat.

How often should I change out my filter socks?

If the sock is clogged and water is overflowing the top, you should have changed it out yesterday. Never let your socks run longer than 2-4 days. Sometimes daily replacement is required if your dealing with a substantial amount of waste or debris for some reason.

The thing about socks is they don't really work unless you remove and replace them, so swapping them out is critical. If you keep up with filter socks changes, they will prove to be one the most highly effective forms of filtration and provide unparalleled water clarity.  If you neglect them, the collected waste will simply be fuel for bacteria further increasing your nitrate and phosphate levels. A wise man once said..."No filter sock is better than a dirty filter sock!".