I have a 12 gallon aqua cude with 3 hermit crabs, one turbo snail , one fire fish, and one yellow clown goby. I plan to add one clown percula. I have a very bad algae problem it is brown and on the sand I stir up the sand and it comes right back in 3 days. I have tried to play with the power head but nothing helps. What can I do? Thanks for your help. The tank temp is at a constant 80 degrees