Likely its detritus. I don't even have a sandbed, run a 100um filterbag and its particle city in my tank. I also run ozone and it helps break down some of the bits but every once in awhile a fish will stir up some crud thats hanging out in the back forty and its snowglobe time. I also siphon detritus on the bottom weekly. I don't really know what to suggest other than that ozone does help (at least I think it does in my tank). :biggrin:

BTW with all those tangs in the tank they're more than likely creating a lot of, um, detritus (poo) so I would imagine its probably difficult to keep on top of unless you want to feed them less. Perhaps try a filterbag that is a smaller micron size. You will have to swap them out more often but it might help.

I also have a "few" tangs and tangs do 2 things. They eat and they pass what they eat so there are always particulates in the water. I use 3 of the 100 micron filter socks and cant imagine not having at least one. I don't think feeding less is the best option because (my) tangs tend to get a bit aggressive toward each other if I cut back their food. I think if I found new homes for my Rabbit and my hippo tang that all the particulates would disappear too. I swear the output on those 2 far exceeds the input. I just try to ignore it for the most part.

Scott

I second that on the hippo tang, one wiggle of his butt and its smorgasbord for the rest of the fish :razz:

I have a fairly heavily stocked tank which includes 4 tangs and a trigger and my water is very clear. I use two 100 micron filter socks in my sump, one for the overflow for "floaties" and one on the return from my skimmer for bubbles.