Is the “scum” turning into a clear then later brown snot strand?Cyano? In Refugium
Recently I’ve been getting a greenish brown scum on the water surface of my refugium. It is likely some type of cyano, but seems to like the surface.
It can become thick enough to scoop out in just a day. I’ve not yet tested N and P since I don’t yet have the kits I want, but will soon.
Turning off the skimmer might be making this issue worse. I don’t have a true overflow from the refugium unless the drain holes become clogged, and I likely don’t want to overflow the scum into my return chamber and then up to the display anyway.
I already have one accessory powerhead to give flow in the refugium, but I may need to upgrade it.
Alternatively, I might ramp up the power in my return pump and divert a lot of the flow into the Brute chain to increase the flow through it without increasing the overflow noise at the display (which has been nicely low).
There’s no sign of this scum in the display or any other brutes, but the lighting is currently low in the display. That could be one an issue in the future, though the display does have a lot more flow and also true overflows.
