What Algae is This and How Can I Beat it?


New member
Every day i have this brown film over the top of my rocks and i rub it off every day with a tooth brush. I dont know what else to do. A month ago i had really bad hair algae i did let my maintenance routine go a little but been fighting like hell to get the tank back on track so idk if its just hair algae trying to come back or something else. My po4 is .00-.02 (checked with hanna checker), my no3 is 12 (checked with NYOS). Tank has been up and running for almost 2 years now.


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Staff member
RC Mod
Can't judge color, but if red brown read up in the sticky note above on cyanobacteria. ^^^^


Premium Member
Brushing it off doesn't remove it from the system and as you are seeing it will settle back pretty quick. I figured out in my maintnenance business years ago teh best way to deal with nuisance algae problems is just manual removal. If practical first thing I would do is remove the top rocks with the worst of the algae and brush them off in a seperate bucket of aquarium water, rinse in another buicket of aquarium water and return to the DT. For ongoing maintenance I'll use stainless steel straws and paper towels as shown in these two videos to remove algae from a system. Be patient, what you are doing is shifting the equilibrium of your reefs ecosystem to favor corals over algae and it takes time. Forest ROhwer discusses this in his book "Coral Reefs in the Microbial Seas", kindle is just $10.

Steel Straws

Paper towels for algae


New member
All my rock is cemented together so that sucks smh this is annoying thought after 2 years i wouldn't go thru diatoms again thats what it looks like


Premium Member
One technique with H2O2 I use very infrequently uses a syrenge and silicone muffin cup. Poke the tip through the silicone muffin cup, hold in place against the rock where you want to kill algae and squirt a small amount of H2O2 into teh cup. Hold teh cup in place for about a minute tehn move on. Be careful not to use too much H2O2 at any one time. I set my limit at 1mm per gallon. This can hurt corals and polyps so I do not put the muffin cup over any coral or polyp, just rock I want to knock back the algae. This likely will need multiple treatments and it's best to wait several days before trying it again to let the tank recover from the H2O2.