Help what is it and how do I get rid of it?


New member
Hello, I am new to the forum and was hoping to get some help. I have this brown mushroom like algae growing all over the tank and I’m not sure what it is and how to get rid of it?


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Premium Member
Wow, I have been reefing for 20 years and I don't know what that is or how to get rid of it. You could try removing a rock it's on and hitting it with a strong kalkwasser paste and see if that burns it. Then rinse the rock off with saltwater before placing back in the tank.

salty joe

New member
New to me too. It looks soft, another option might be to siphon it off when you change water. It could be that whatever is fueling it gets exhausted and it fades away. Following for sure!


Premium Member
Looks like a sponge with brown algae growing in top. If si0o it should pull off essily and be easy to mash. It's possibly feeding off DOC in your system. Regardless I'd review everything that's happened or changed in the last 5 or 6 months to figure out why it's doing so well.


New member
Thank you all for your responses. It is very soft and it tends to float and then get caught in powerheads / overflow. I will take the suggestions of trying to siphon it out and remove what i can see but the issue is it keeps coming back and is very aggressive and on all rocks and will grow on the glass and overflows as well.


Premium Member
Reef tanks are awesome. It literally looks like terrestrial fungus. Does it spring up fast or has that been developing for months?

Sugar Magnolia

Mother of Dachshunds
Staff member
RC Mod
Very interesting! I was just scrolling through Bob Fenner's FAQ's on sponges at WetWebMedia and didn't see anything similar in the sponges but one thing I saw was red throated Ascidians. ?‍♀️

Your phosphates may read 0 but whatever those are, sea squirts or sponges, they are thriving in your system due to nutrient dense water which means it's using the nitrates and phosphates to grow.