Ahhh, one of the biggest benefits of having an overflow into a sump. However, the only real good
thing you could look at is that you do at least have an indication that you have an abundance of DOC
's. All the above choices will work, but some require extra equipment being visible in the tank.
What I would do first is remove the DOC
's causing the problem. A large water change of 30-50% would probably do wonders in addition to running carbon if you have the ability (HOB
/Canister filter, etc.). It is most important to make sure the changewater is properly mixed, aerated, and buffered to the tank parameters (PH
, salinity, temp).
The accumulating DOC
's on the surface may actually be a sign of more impending problems down the road from lack of export.