Not sure what is going on....

[Elbowdeep]

like the title says lol rocks are getting like black spots almost like where Coraline would be. I just switched from a 85gal hex to a 90gal standard. Notice this in the hex also. Read something about hex tanks not having alot of surface area for the tank depth so o2 gets depleted alot faster. The 90 had been up for almost 3 weeks now. Total time almost 1 yr between the 2 tanks. Should this be a concern?

90gl 30gal sump
Ph 8.1
Phos. .25
Cal 460
Mag 1250
Salinity. 1.027
Temp 78.0
Nit 0
Nat 0
Light is a 48in reef breeders led
Skimmer is a etss skimmer
Any help would be great. Oh started with only dead rock about 50lbs then bought 100lbs Marco dry rock and added 2 pieces of LR to seed tank but still no coraline. Just this blackish. Thanks in advance Jeff.

 

[Elbowdeep]

The coraline I did get on the LR just seems to dissolve slowly one rock still has some but only the part that is not in the direct light.

 

[Elbowdeep]

Any ideas?

 

[BlueCursor]

Hard to tell from the pic. Shine a flashlight on it. Is it a dark green or actually black? If it is black spots, probably black sponge. Nothing to worry about. I had a big outbreak of it when I setup my tank, 6 months later it was all dead, unfortunately. Would have been nice to have some grow.