[doggybaggs]

Just added MH to my new tank. How before my live {?} rock colors back up?

[Reefland]

Hi doggybaggs,


Are you talking about coralline (purple) algae? If so, it isn't the lighting as much as it is:
1. Having some coralline currently present.
2. The proper water conditions, including calcium and alkalinity.

[rjs5134]

Scott, I think doggy... read a thread that said the change to intense MH lights may bleach the corraline algae, which may or may not acclimate to the new light(all from memory). I changed from PC's to MH's last August and the CA "bleached" especially on the glass and has only returned to it's previous condition on the rocks, not the glass. The thread also said that CA prefers less intense lighting.

Rob

[charlie]

When I changed from PC to MH, the coralline on the glass went pink, but the algae on the rocks stayed purple.
5 years later the glass is still pink in that tank. Coralline seems to grow for me in any lite condition, but it does seem to be better in the lower lite. HTH