to filter sock or not.... that is the question

[dkeller_nc]

One of the reasons that I do not run mechanical filtration beyond a skimmer is practical experience - in the early 90's I designed my largest tank's sump with sponge block filtration (filter socks weren't around then). I figured out very quickly that it was unnecessary - the buildup of detritus was pretty minimal, and the nutrient export of the skimmer along with occasional water changes was all that was necessary to rapidly grow LPS and some SPS corals.

However, modern reef keeping is somewhat different, at the least the way I roll, in that a great deal more food is being placed in the tank via phyto & zooplankton additions. Nevertheless, and even with only vacuuming out the sump about once every month or two, the detritus buildup is minimal.

But probably more importantly (at least to me), mineralized nutrient levels have stayed very close to the detection limits of the wet chemistry tests. DOC has also stayed very, very low. I attribute this to a couple of things: much more effective skimmer designs, and carbon dosing.

And I still don't have to run filter socks.

 

[NTP66]

I was running a sock on my 90g FOWLR up until a week ago, when my last one was removed (still waiting on a replacement to be delivered). So far, I see no real difference in the water quality. I'll probably run it like this for a while just to make sure WQ isn't really affected.

Somebody mentioned this earlier, but this is probably one of those things we can consider to be personal preference.

I laughed when I got home from work yesterday only to find that the sponge filter in my sump, which sits between the skimmer and return areas, had clogged up thanks to the lack of a filter sock. The water level had risen to go over the top of the baffle, and my ATO dumped a few extra gallons of RO into the tank, lowering my salinity to about 1.023. Nice.

I'm going to take this as a sign to get a new sock in there soon, and replace the sponge.

 

[sirreal63]

Just my point of view here, this is the Advanced section which is a great place to think outside of the box. I will not tell anyone to not use a sock but I don't use them, I do not see a real need. Some things to consider...

A 200 micron sock will trap anything 200 microns or larger, until it does collect things at which point the pores begin to close down and get smaller, enabling it to filter smaller and smaller particles until it clogs and overflows, this is how all filters work. So what is it filtering? It is indiscriminately filtering waste products and living creatures (planktonic life and larger) which perform a function and are also a food source.

A sock or any other mechanical filtration will not capture 100% of planktonic life, some will remain but in most tanks there is a very low quantity of planktonic life and it makes no sense to remove it and deplete it's numbers further.

Detritus happens, but because it is there should not automatically mean it is a problem. I took my tests this morning, PO4 was .01, lower than I normally run but within testing margin. NO3 was undetectable with Salifert, as it usually is and I prefer it to be around 5 and feed heavy to try and keep it at least measurable. The end process of the consumption of food is mostly devoid of any nutritional items, it is benign bulk that has no benefit or harm. I could filter that out before anything has a chance to eat it, but why, it has been feeding things that I want in my little ecosystem.

This is a pic of my sump, in the place detritus normally settles, It has been a couple of months since I last cleaned the sump, I will clean it next water change or perhaps longer.

According to some of what has been suggested my nitrates and phosphates should be high from all of that rotting poo in my sump, but it isn't. Why? It is certainly plausible that I have enough life in the tank to consume the input of food and enough export to prevent it from becoming an issue. I also intentionally feed extremely small particles of food to the tank, pureed seafood items that are so small the fish can't eat them but they help feed the rest of the creatures in the tank, about a fourth of my food is this fine mix. These creatures would not stand much of a chance if I used a sock. I do have a lot of sponges, and I mean a lot, my rocks are covered in sponges that have grown a lot in the past year and a half when only a few small pieces were there after setting up the tank. About 90-95% of my rock was freshly acid washed prior to starting this tank in our new place. Sponges are your friends, if you don't have much sponge growth, consider why.

I do not wish to tell people not to use a sock, but as in all things sometimes you need to look at what you are doing and consider if it really has value or not. I see no need in trying to create a sterile, nutrient void container of water that I am encouraging life to grow in. If you choose to do so that is fine, but at least consider why and what the effects are.

People often notice their tanks do better after the one year mark, some sooner and some later but there is always a point where the life in the tank has reached a point where nutrients are easier to control, growth is consistent and the tank is fairly stable. Why is that? It takes time for all of the biological entities in the tank to reach stasis. You can certainly reach this point with mechanical filtration but it isn't beneficial to do, it just seems like it is and you may be slowing down the maturity of the tank and limiting the biological life that helps to control excess nutrients. Maybe you are not, but judging by the number of people on this forum daily with problems it stands to reason that some of the things we do may be contributing to problems instead of solving them.

Just my long take on the subject, please do what you think is best, but don't be afraid to examine what you are doing and why.

 

[Duna_]

Sponges are your friends, if you don't have much sponge growth, consider why.

I agree.

In my tank there are sponges of all colors (pink, white, yellow as yours, purple, magenta, grey and black). They grow well with the planktonic life from the water. They are the best indicators (along with tunicates) of the water quality and enough food available.

I had been running a sock for 4 months, four days ago I bought live rotifers, feed them ... stopped the return pump, and those which weren't eaten went later directly to the sock. I felt as I have done very little, the small particles of microfood also are wasted.

And everytime I touched the sock or changed it, the skimmer went crazy. I hated that ...


So I took the sock out and put a plastic vertical jar-tupperware to slow the flow and settle the bigger particles in it, so water flows over the top part.

With the sock I also had to siphon the sump, but now the particles can feed other creatures. I have the chaeto in a floating cage made of plastic net, so the bottom of the sump is free and particles can settle there.

 

[mos90]

i have 2 sock holders in my sump. i only use 1 and change it out every other day. im debating on stopping the use also. there are always pods caught in the sock. i might just use them when i clean the sand.

 

[sirreal63]

im debating on stopping the use also. there are always pods caught in the sock.

Those are just the ones you can see, many others you cannot.

 

[slief]

Mesh filter socks rarely if ever clog.

Very true but mesh socks don't seem remove any where near the same amount of stuff from the water when compared to the same micron felt socks. I ran 200 micron mesh socks for a while and was not impressed with them. I might try 100 micron mesh socks to see how those compare to my 200 micron felt socks.