Can the lighting "bleach" the purple color off of the rocks?

[Kissfan79]

Hey guys....
I have a question about lighting and live rock. Can the lighting (MH with PC actinic supplementation) bleach out the purple coloration from live rock? The reason I ask is that it seems that the rock in my tank that had a nice purple coloration has faded. My magnesium is around 1300 and my calcium is a bit low at 360-380 but I took notice of a piece of rock I turned over the other day. It was DEEP reddish-purple....tons of color. This was about a week ago and I have already noticed a marked reduction in the brightness of the color on the rock. I thought it may have been my imagination with the other rock but this was very noticeable. I know the coraline is growing as I have rocks that are getting some coloration and the back wall and overflows are covered in purple. I was just wondering if the lights could bleach out the live rock color.

Thanks, Jim

[JFisheez]

not likley, if u have any turbo snails or urchins they love to eat that coraline which doesnt get rid of the coverage but just the purple color.

[d3rryc]

Same goes for asternias, a type of small starfish. I had to get a harlequin shrimp to help control the number of asterinas in my tank b/c they were eating all of the coraline off the rocks in my tank.

[psteeleb]

Yes - coraline does not like intense light. It needs light but too much can kill it. When I increased my light intensity a lot of mine faded away. I get great growth in shaded areas, my overflows and sump. But areas exposed to direct light, not much.

As mentioned some snails and other CuC munch on the stuff also.

[crvz]

I don't think turbo snails eat coralline, but urchins will. In any case, I have found that coralline is more susceptible to die-off from lighting changes than most things. But you didnt indicate any changes. I've also experienced a die-off after a calcium reactor mishap, which dropped alkalinity rather dramatically. Any story on the alk in your tank of late?

[Kissfan79]

The lighting on the tank is an outer orbit with 3x150 watt halides and 4x96 watt PCs. The alkalinity is usually a bit low at 8 dKh but I haven't noticed any big swings in it. The effect I am referring to is somewhat akin to leaving a magazine on the dashboard of your car. When you put it there....the cover is nice and bright...crisp with color. After leaving it there for a day or two...it still has color but is all faded. That is what seems to be happening....the purple color is still there....just faded.

Jim