[aneely]

I have a 150-gallon reef/fish salt-water tank, 48" length, 24" wide, 30" depth. I have two 48" Hamilton fixtures for my lighting, each with 2 - 175 watt bulbs. One fixture has 10k lamps and the other fixture has 12k lamps, the 10k set comes on first, while the 12k set comes on when the sun should be it’s brightest. The 12k will stay on for about 5 hours then shut down, leaving just the 10K on by it self. Now keep in mind my blue actinic lights start and end the day on first, and off last. Ok my problem, my live rocks are turning very dark in color, not algae, and I am getting a lot purple stony buildup on the sides of my Acrylic tank. Any suggestions, as to what's going on with my tank, thanks?

[Poseidon]

Thats called Coralline Algae... It is a sign that your Ca and Alk levels are in good proportion. Take a look at Ninongs tank in progress thread he has excellent Coralline growth on the rocks, or look at my B4 and after Kalk thread it will show all the Coralline growth I had in the 3 months or so....

[Reefland]

As for the rocks getting darker, it is common and different life starts to encrust them. Sounds to me like your tank is well on it's way!

BTW, Welcome to Reefland!

Scott Z.

[aneely]

Thanks for the advice.