White Fuzz on Rocks

ReefJedi · Apr 27, 2019

I have white fuzz growing on my rocks. Seems to affect only the top of the rocks (facing the light) but only on rocks towards the bottom fourth of my tank. Can’t figure out what it is.

Hitman · Apr 27, 2019

How old is the tank?
Was it filled with tap or RODI water?

Mike.P · Apr 27, 2019

More than likely, and based on how much algae you have on your rocks too, it's a bacteria overgrowth. Possibly a fungus, but I don't think so... An easy way to test this, is with methylene blue. Pull out a chunk of it, and dip it into the methylene, or smear some on it; if it's fungus it will stain blue, whereas bacteria will not.

ReefJedi · Apr 27, 2019

I'm using RODI, 0 TDS.

Tank is about a year old but I bought it two months ago. It was neglected for a few months by the previous owner and it had this fuzz back then too.

Methylene blue? If it figure out it's fungus what should I do? Scrub it?

Mike.P · Apr 27, 2019

ReefJedi said:
I'm using RODI, 0 TDS.

Tank is about a year old but I bought it two months ago. It was neglected for a few months by the previous owner and it had this fuzz back then too.

Methylene blue? If it figure out it's fungus what should I do? Scrub it?

It's a chemical that's used for testing, but can also be used as a supplement/treatment for marine tanks, so it should be available at just about any LFS; if not, just get it on Amazon. If it's fungus, there are antifungal treatments that you can start... In any case, I have a feeling that your nutrient load is pretty high, maybe due to over feeding, not enough filtration, etc., so you should look into that as well. That's typically what causes these blow ups. With how much green algae you have on your rock, I think that's your underlying issue.

MelnTam · Aug 6, 2020

ReefJedi said:
I have white fuzz growing on my rocks. Seems to affect only the top of the rocks (facing the light) but only on rocks towards the bottom fourth of my tank. Can’t figure out what it is.