ID Help, Please!

[Cari]

This looks and acts like Cyano to me, but certainly isn’t red and research I’ve come across says “green or blue-green”cyano rare.

Background:

90 gallon

Salinity 1.031. Milwaukee Digital Refractometer and hydrometer (not sure why so high...has been stable at 1.026 for 10 years) anytime top off has a hiccup, it’s been remedied quickly with minimal effect on sump levels. I suspect a culmination of “hiccups”. Should be able to adjust this relatively easy.

Ph. 8.29. Pinpoint
Ca. 555. Hanna
Alk. 7.4. Hanna
Ammonia. 0. API
Nitrite. 0. API
Nitrate. 40. API
Mg. Off the charts! Salifert test (exp 10/20) if I’ve calculated it correctly 2610. (One syringe and a part of second (.26). Total of 1500+1110.

No phosphate test (ran out)

Within the last few weeks, I pulled out a Huge growth of gsp and removed some rock, which increased the nitrates, I’m sure. Last week nitrates were 20. Was running Algone and this week they are 40.

I have 2 Green Machine UV sterilizers running, with minimal effect.

I will be scheduling a water change. The tank has had distilled water from inception. I have a 10 gallon reservoir, so have to pull off water change amount over a few days. How many gallons would you change out to start?

Other than this ugly green stuff, fish and remaining corals look happy. The only thing that obviously suffering is Rbta. I use to have so many, that I sold them to local lfs. Now trying to save what’s left.

Thanks for ideas and help!

 

[EmdeReef]

It certainly could be green cyano. What’s the texture like? You could try taking a sample and adding some hydrogen peroxide to confirm. 2 cups aquarium water, 1ml of 3% peroxide. Let sit a few hours if water turns green it’s cyano.

 

[Cari]

To me the texture is like red cyano. It will blow off rock with turkey baster, some of it in very small sheets. The pieces on the sand look like they could lift off in a “mat” but if you tried to do that, it will break apart. Touch feels somewhat slimy. It will get tons of air bubbles if left alone. I will give test a try. Thanks for prompt reply!

 

[Cari]

Ok, I performed water test. The water did NOT turn green. So I assume that means I’m dealing with an algae and not a bacteria? If that’s the case, any idea what kind of algae it is? And which cleanup critter might enjoy this munchie?