Please give me good news. What is this blooming?

[mcgallagherc]

So, I was having an issue with undetectable nutrients in tank. Dosed for nitrate and that got up but the phosphate was still undetectable using saliferts kits. I unplugged skimmer, didn't change sock filter for 10-14 days. I also just bought Hannah checkers and checked for phosphate and still got a 0.0 reading(earlier today) About to check alk and nitrate. Is this growing a major concern?

 

[Tired]

Looks like cyano. Blow at it with a baster and see if it comes off like slime. Not a surprise in a tank without any nutrients to grow competition for it, but could also mean high organics.

 

[mcgallagherc]

Just used Hannah checkers for first time.

Po4- .04
Nitrate- 22.1
Alk- 9.7

Using salifert kits 2 weeks ago I was undetectable on nitrate and phosphate. Nitrate started climbing but phosphate was still undectable as of Friday.