For the past week....2 weeks, I've dealt with what appears to be algae. It is brown, slimy (then again so is the whole tank wall xD). Now it usually randomly pops up every Sunday before the water changes (Monday). So usually, I just take a small sponge and wipe it off the glass. Now it appears to be on the croc skull and the sand.
Not sure how I am going to remove it from the sand.
I have a fluorescent bulb and the tank also receives natural sunlight from the window. But the sunlight doesn't reach that far into the tank, one would think that the algae would grow along the walls and items closest to the sunlight.