We had been having major problems with a slow, creeping brown slime across our sand, when we turned to Fenner and realized we had an oxygenation issue. I assumed that given the surface area of water in our tank, the skimmer, and the refugium, it wasn’t even something to worry about. However, the description (“smelly, brown bubbles rising to the surface”) was too exact, and I’m convinced that’s the problem.
In addition to using a venturi filter in our refugium (just the maxijet and venturi, no skimmer), I’ve been using a turkey baster to churn up the detritus in our water. After ten minutes or so, it looks like the picture below. Here are clowns in the mist:
It gets better every day, as the clouds of waste get churned up and caught in the skimmers, but I always feel like the fish hate me. In the sea, storms roll through and roil the sediment, and in our tank, it disapates after an hour or so. By the next day, the water is so clear it feels worth it, but I always have a pang of guilt seeing the immediate result.