black marks on crs.

[imke_j]

I want to jump in here again as not only bacteria can give that black marks look but high NO3 (Nitrate) also, as I have been told lately. If you have contaminated water with high NO3, the duplication of the cells can be disturbed (like from P=4 also), and it can give the reds a brown or black look. We shrimp keepers should hold NO3 as low as possible, what not always is easy, as some tap water already comes with 30-50 mg/L.

[ocin]

looks like all my crs have been cured, black marks disappeared, but im confused with my cbs.. the black part is just not clear with some red marks...