Black growing on live rock and sand

[Timsreef#1]

Can anybody identify this Black growing on live rock and sand

 

[lmforbis]

Cyano bacteria

 

[Timsreef#1]

Thanks I guess it's time to test for phosphate and maybe another powerhead

 

[Timsreef#1]

now it's pretty much covers everything and all the fish died any ideas

 

[lmforbis]

i need som stats on your tank
size
age
fish before they died
water parameters
lighting
erc