TL: DR at the end...
I am having this same problem of white cloudiness both in the tank and the reaction chamber of a recently broken-in sulfur denitrator (Korallin S1502), although my effluent does not smell like rotten eggs. If anything, my effluent drip rate has been too high so I do not believe it is hydrogen sulfide. This is the second time this has happened, and in both instances it has also been associated with my protein skimmer not skimming.
The first time it happened, I had turned off the protein skimmer the night before (frankly I can't fathom why), and the next morning there was white cloudiness in the tank and in the reaction chamber of the denitrator. Based on the differences in concentration of cloudiness in either location, common sense would dictate the white stuff was being created in the reaction chamber and then distributed to the tank, not the other way around.
The second time it happened was yesterday/today. Last night I went to bed with everything running smoothly. This morning, I noticed two things: one was the water level in the protein skimmer had dropped dramatically, so far in fact that there was no way for the skimmate to reach the collection cup, therefore no skimming had been taking place. The other thing I noticed was the tank and the reaction chamber were ever so slightly cloudy again. Notice in the first case that the lack of skimming predated the cloudiness, therefore I'm assuming in the second case that the water level in the protein skimmer dropped first (thereby stopping the skimming action), and _then_ the denitrator got cloudy.
Keeping in mind, the denitrator has been running for a few months so the sulfur should be adequately colonized according to the manual and all the various forum threads I've researched. Everything has been going exactly as the manual said it would; I have not had any of the common problems reported by other sulfur denitrator users (such as bubbles forming in the top of the chamber, etc). So I'm confident I'm breaking in the denitrator correctly. However, I am still in the process of finding that perfectly balanced drip rate, which is basically as fast as possible to maximize nitrate reduction in the tank and to minimize the risk of hydrogen sulfide production, but not so fast as to allow nitrites/nitrates to survive the exit back to the tank. And I'm not there yet; I've still been gradually increasing the drip rate every day, which I began after "baselining" my drip rate at the rate necessary to fully eliminate nitrite production. That, combined with the fact that I detect no rotten egg smell, leads me to believe that a too-slow drip rate is not my problem. However, I concede that perhaps the denitrating bacteria are still multiplying even though the denitrator has been running for several months, and perhaps they are multiplying so fast that my daily increases in drip rate are still not enough to keep pace? If so then why no rotten egg smell accompanying the cloudiness? Or is my drip rate becoming TOO fast, causing some reason for bacteria in the chamber to release into the water column, and THEY are causing the cloudiness? Then again, I'm skeptical of that explanation as well because nitrites in the effluent remain at absolute zero, which tells me my drip rate is not too fast. I'm so confused.
Also keep in mind, this denitrator is the type that includes a crushed coral layer above the sulfur layer for the purpose of buffering kH and calcium. I have no idea if this is material or not.
TL: DR A halt in protein skimming seems to cause some sort of bloom within the denitrator. Why?
