reefgeezer
Active member
Well I was excited but now it's coming back.
Like I said earlier, IMO, you may have a dissolved organic problem. Looking at your tank, the bioload is not that high so I'd look for something that is not operating properly particularly the skimmer.
What skimmer are you running and what is the flow through it? Is it producing a lot of skimmate? What color? How much?
How much flow through the sump?
Is the current in the DT sufficient to keep detritus suspended until capture by the overflow?
How often do you change GAC?
Are you vacuuming the sand, rock, and sump regularly?
Are you adding any carbon (organic) compounds? Alcohol, sugar, some calcium supplements, vitamins, amino acids, vinegar, salt mixes that have vitamins in them, etc. can all feed cyano.