live rock turning white?

[Ktm898]

my tank has been established for 4-5 months. I am now having a problem with my rocks turning white. What would cause this. My fish, candy coral, mushroom,and zoas are doing great.

 

[JOKER]

Have you recently upgraded lights? Lot of time that will kill It off for a bit.

 

[Ktm898]

2 months ago i went to a 4bulb t5 setup. I cleaned the salt creep of my plexiglass tops a few days ago. Could that make enough difference? only change happened last month, this was phosgaurd after high phosphates.

 

[JOKER]

Yes I think it could