Went out of town and wrestled with whether or not to use a feeder block. I wish I hadn't. I came back to this mess all around the block. It's only turning brown in the area pictured. It's a 65 gallon and that spot is right in the center. The sand is still bright white on the left, right and back of the tank. My parameters are all great. It IS a new tank though. I've only had fish in it for under a month. It is a cycled tank. Is this diatoms or cyano
, or something else?
I read that diatoms thrive on low light, but this seems to almost clear up by morning after having the lights off overnight. It progressively gets darker again during the day. This made me wonder if it may not be a diatom issue. It's been a week now since I've been back home.
Oh yes, I should add that my Mollies seem to eat it? They scoop a bit up, then spit the sand back out. Don't know if that helps or not. I found it interesting.