<a href=showthread.php?s=&postid=8731632#post8731632 target=_blank>Originally posted</a> by mr.wilson
You have a phytoplankton bloom. It's usually caused by limited flow, over-illumination, and growing pains of a new system. You can eliminate it with one or all of the following...
1) U.V. Sterilizer: Set the throughput slow enough that you get a high kill ratio.
2) Add rotifers: This never worked for me, but many swear by it.
3) Diatom filter: Use a micron filter bag or a Vortex Diatom XL to remove them. You don't have to use the diatom powder, but it removes smaller particles and makes the filter bag much easier to clean.
4) Discontinue lighting: With base rock, there's no need for lighting until the tank has stabilized (two months).
5) Water clarifiers: This should be done in conjunction with #3. I use Kent Pro.Clear or Seachem (Clarifier?). These polymers will lower the dissolved oxygen rate if you overdose, so follow the manufacturers directions and consider displacement from rocks etc. They act as a coagulant and either "choke-out" free floating algae or bunch it up enough to make it heavy and easier to trap with mechanical filters.
6) Phosphate remover: Base rock is a phosphate and silicate sink. You'll have to inoculate your system with bacteria, as your rock and lack of substrate will slow the cycling time greatly.
7) Increased flow: Try to move as much water from the bottom of the tank up to and across, the surface. How much flow do you currently have? Does your surface skimmer remove all oils and other surfactants from the surface?