I recently returned from a conference in Australia, only to find my tank was covered in brown stuff. It looks like some sort of algae, but I’m not sure what kind. A few things happened — about 2 days before I left I received an order of mangrove jellies. I switched the wave maker to a different spot to try to keep the jellies off the outtake mesh. My bubbler also crapped out. This means that 1) new water was introduced into the tanks 2) the feeding regime changed and 3) new waste was being produced. Before they got there, I checked the tank chemistry and everything seemed within reasonable parameters. I did a bit of cleaning and a partial water change. I also had a student and my husband looking after the tanks. Both are completely capable, but not as familiar with the tanks, so there may have been some overfeeding. The pH in the tank has been dropping too. I added some stabilizer, but that didn’t do much for the pH. So I added some buffer to raise the pH. We’ll see if getting the levels back to where they were. I also installed a new bubbler to break up the surface some. It could be some of the filter feeders under the algae too, I’ll have to check them when I get a chance. The jellies at least don’t seem bothered by the brown stuff, and they are the primary research concern. I’ll see how things are doing in a few days and maybe do a water change on Sunday.