What is this film on my rocks?

[shimmer]

And what can I do to get rid of it?

Tank is somewhere around 6 months old. This film is covering a significant portion of the rock/surfaces in my tank.

It's mostly white with some green and brown in it. Easily blows off. Causing, or related to, a bloom, either bacterial or algae, in the tank right now.

It's been a thing for a while, was getting better, then came back worse.

Nitrate and phosphate are near undetectable.

 

[Sophie"s mom]

If the tank is about 6 months old, have your nitrate and phosphate always been near zero? That is not good for a tank. What are all your parameters? Do you have a UV sterilizer?

 

[The_Paradox]

Looks mostly like detritus. What is flow like in the tank and what kind of filtration?

 

[shimmer]

Sal-34ppt
PH-8.15
Phos-0-0.03ppm
Nitrate-0-2ppm
Alk-11.5dkh
Cal-460ppm
Mag-1500ppm

Somehow had a mag spike, up to about 1575 after I thought I had it dialed in, so I quit dosing it to let it slowly come down.

Filter is carbon, purigen, and floss in a submersible filter and Reef Octo HOB 2000 skimmer.

I only have one fish, a goby that eats just about every pellet I could possibly put in the tank.

Nitrate and phosphate haven't always been zero, but have been for two or so months now while all of this has been going on.

No UV.

Flow is pretty good, almost everywhere, it's a 60 cube with a jebao scp 90 turned up about 75%. Could be better in a couple spots, but overall it's pretty high flow.

If I blow it off it's pretty well covered again in 24hrs, completely covered again shortly thereafter

 

[The_Paradox]

I would try adding a flocculent to see if that helps capture whatever it is. If it’s coming back in minutes there has to be a fair amount of particulate in the water.

 

[shimmer]

I do. Was doing coral snow every other week, but I was afraid it was maybe adding to the buildup so I haven't done it in quite some time until last night because of the bloom. It did help clear the water up.

 

[shimmer]

I believe it is some kind of film bacteria. Going to try microbacter clean.