Everything looked fine until I went on vacation two weeks ago for a week. I got home and I thing our pet sitter turned off the air condition. The tank temp was around 83f when it it usually in the 78-79 range. I noticed this growing on the sand and now it’s spreading on the sand. The pic below is what I had the first time. Does not look the same to me but I’m not sure. Thanks
Lights are two ReefLED90 at 23-20-23k from 10am to 9pm.
Nitrates 5
Phosphates .02 Ulr Hanna checker
Salinity 35ppt
Temp 78-79
Magnesium 1350
Alkalinity 8