Should I be worried.

[cjp847]

Hi everyone I have a 40 gallon breeder with crushed coral that's been up and running for 6 months. And about a month ago I started seeing this bluish /black algea What is it, should I be worried? I was planning on removing the crushed coral. And replace it with sand. My cal is in check at 440 my alkalinity is at 9ish(depending on what test I use). Any ideas and help. Salinity is 1.026. Thanks in advance!

 

[cjp847]

I've done the 3 days no lights. And it went away. As soon as I turned them back on, it was back.

 

[RJinPV]

It sounds like a form of cyano bacteria algae. What are your tank parameters, especially nitrate and phosphate?

 

[cjp847]

I'm waiting on my phosphate test kits (should be here tomorrow, Salifert). Nitrates look a little high. From what the api test kit shows, 20 ppm.

 

[cjp847]

I must have did something wrong This is a test I just did.