Help I'd this algea

[Anthony christian]

Ok I have a 280 gallon system it is 3 months in and I have had all parameters in check I tested the other day all was great

P04 undetected 0ppm
No4 0ppm
No3 0ppm
Amon 0ppm
Cal 420 ppm
Alk 7
Mag1650
PH 8.2
Sal 1.025

Last few days I have had some brownish stuff on sand it's not diatom I assume it's cyno but can you help me Id it so I can treat and find the reason for it. Pic is attached

 

[Anthony christian]

I will add that the red in pic is from lighting and shimmer effect in ta k it is all brown in color but kinda stringy that's why I have not come to the conclusion of cyno yet just no traces of red

 

[Toadfish]

Looks like cyano to me, yeah. There's a few varieties of varying redness, but the stringy look is pretty typical. The only thing of note to me is your magnesium is very high. Don't think that will do anything to cyano good or bad, but something to keep an eye on.

 

[Anthony christian]

Thanks that's what thought

 

[Reefing Madness]

Yup, Cyano