my tank has been set up for 3months now it is a juwel rio 180 i have the original filter running aswell as a aquaone cf1000 external filter and a 3000l/h powerhead. I am now getting brown algae on my rock and sand what can i do about it? I have a blue damsel and black and wite stripe damsel and a yellow clown gobby. I feed every other day a somtimes frozen cockel meat or live food.