What is this stuff growing on my rocks?

[RussC]

Its gray. Appears to only be growing in areas facing the lights. Appeared rapidly and spread/grew throughout aqua scape. its very slow growing. Is slimy to the touch. Comes off easily if vacuumed or rubbed but returns next day. All measurable parameters are excellent and have been well within appropriate ranges for some time. This is new to me. Been doing this for many years but not seen this. Very low nutrient system. My working theory is maybe I overdosed on "good" bacteria and created a bacteria bloom of some kind. Stumped and looking for ideas and help.

 

[kharmaguru]

Yes, looks like a bacteria or even cyano (because it likes light). What is your phosphate/nitrate?

 

[RussC]

Phosphate .01
Nitrate 2

 

[griss]

Yes, looks like a bacteria or even cyano (because it likes light). What is your phosphate/nitrate?

Agree.

 

[RussC]

I was considering treating with chemiclean. Truly, probably wouldn’t hurt to do it. Honestly, just a pain dealing with the process.

 

[kharmaguru]

I was considering treating with chemiclean. Truly, probably wouldn’t hurt to do it. Honestly, just a pain dealing with the process.

It is a hassle and I wouldn't do it unless your tank is overun with the stuff and other methods have failed.

 

[jason2459]

I've seen green and red cyano. Don't think I've seen gray/opaque before.

Are you sure it's only growing in lighted areas? Seems like some good flow there too? Cyano typically doesn't grow out like that in a high flow area.

To me it does look like a bacterial mass of some kind.

Do you dose any carbon sources like nopox, vinegar, ethanol, vodka, citric acid, sugar, etc?

 

[RussC]

I've seen green and red cyano. Don't think I've seen gray/opaque before.

Are you sure it's only growing in lighted areas? Seems like some good flow there too? Cyano typically doesn't grow out like that in a high flow area.

To me it does look like a bacterial mass of some kind.

Do you dose any carbon sources like nopox, vinegar, ethanol, vodka, citric acid, sugar, etc?

I don't dose with any of those elements you mentioned. You can see why I'm a bit stumped. This is a new one on me. Outside orf automated water changes, alk and CA, I dose Microbacter7, Acropower and Dr.Tims Waste Away. But I've never dosed those at full dose per the instructions. However, I did increase the dose about 50% about two weeks before this showed up. So I've begun cutting back on what I am dosing and will do so a little each week to see if something changes. When I looked at my notes and saw I had increased my dose on bacterias, This lead me to think maybe this stuff is bacterial in nature. For lack of a better word, "overdose" on good bacteria.

 

[griss]

For lack of a better word, "overdose" on good bacteria.

Sounds like you solved it