Remove red algae from a saltwater aquarium by removing it by hand or filtering it out. Make adjustments to the lighting, nitrate and phosphate levels. Replace rock or sand, increase water flow and add some algae-eating fish.Continue Reading
Siphon the algae out of the aquarium with a hose or filter the water by hand using a net or a small filter.
Adjust the lighting up or down depending on whether it is bright or low.
Change the levels of nitrates and phosphates by lowering them until you see no more algae. Test the water periodically to ensure that you are not lowering the levels too much.
Remove the rocks or sand and replace it with aragonite types of rocks or other substrate. While you are switching out the substrate, increase the water flow at the pump because red algae grows more in a low-flow tank.
Purchase algae eating fish to help remove current algae and to feed on any that might grow in the future. Some types to consider include those from the macroalgae species. Angelfish, tangs and surgeonfish are also good choices.