I run four 7" 200 micron felt socks in my sump 24/7. I've been running them for 6 years now and never seen any downside to having them. Only upsides. My sump remains detritus free and contrary to popular belief, they aren't "nitrate factories". That is a complete misconception in my experience. If you don't have socks, any solids that they could have removed will be left in the tank to break down. As such, if some solids begin to break down in the socks between sock swaps, that's certainly better than all the solids remaining in the system to break down. Lower nutrient systems could see minor adverse effects from the socks in terms of the water being "too" clean but that is pretty rare. As far as pod removal, pods generally stay in or near the rocks and substrate. Any pods that find their way over the overflow and into your filter socks should be inconsequential in the grand scheme of things and shouldn't make a dent in pod populations. Fish will consume far more pods than the socks. As far as sock change intervals, that in my experience varies from tank to tank. I change mine out ever several days when they start to back up and overflow. Some tanks will clog socks faster depending on the sock size, number of socks, flow through the socks and of course the amount of solids in the water.
Bottom line, I am a firm believer in filter socks. I think people tend to get too anal when it comes to changing them out so frequently. The misconception of the nitrate factory thing leads people down that path. I surmise that if you are having nitrate issues, you have other problems and the socks are the least of them. Things like having enough bacterial surface for bacteria such as enough live rock, sand, DSB's etc play a much bigger role in nitrate control that sock change frequency. Reducing solids in the water can also help in that regard as can a good skimmer but enough bacteria in a healthy system is the biggest factor when it comes to maintaining low levels of nitrates. I have over 60 fish in my system with many being large 8" + fish and feed 3x a day and tend to over feed with my nightly feelings. My socks are changed ever week and sometimes even longer and I have no detectable nitrates, no nuisance algae issues and I don't dose carbon sources either. I attribute that to a well established system with a lot of live rock, a remote DSB in my refugium and lots of good flow to prevent detritus build up in the display coupled with filter socks and a great skimmer to export the solids from the system.
