Help!!! I have mold growing over my gravel; I have a 30 gallon, community tank that gets a partial water change--around 30% once a week. I have a bubble rod, heater, and 3 stage filter along with led lights on the hood. I have a clean up crew of I standard Pleco, 2 cory cats, and three yoyo loaches. Also 2 neon tetras, 2 Danios, 2 black skirted tetas, 2 Congo Tetras, 4 diamond tetras, 5 Platys.Most of my plants are plastic. I have pink and black gravel on the bottom, and a stump with plenty of holes in it, a dinosaur ornament that fish can hide in , and a white rock with holes that the loaches love. The fish seem healthy, and I just found the patch of mold today.Where did it come from? Is it deadly? How do I get rid of it. I also had a red betta in my tank and had o remove it because it became mean to the other fish in the tank and bit some to death. He is in a separate bowl in the kitchen now. Can I put him back into the community tank at a later time and expect him to be a good neighbor? Thanks for any help.