Question about distance from mh for my crocea

[deansreef]

Hello all I have a crocea clam about 12" from a 250w 6500k metal halide for 10hrs a day it seams to have bleached right by the intake hole and dr knops book says it could be the lighting any ideas? Dean

 

[toptank]

If you are referring to central bleaching he stated 2 different things about that.

Loss of symbiotic algae in the area affected. The cause of this is however, is not clear.

then 2 paragraphs down he says.

Animals with pronounced central bleaching will die if exposed to a high-output light source.

then

If the distance to the light source is increased, the condition seems to improve, however, the degeneration process in the tissue will not stop, only slowed down.

IMO & IME, I don't think 12" is that high between the light and the clams. Now you will have more temp closer to the top than say lower in your tank.

Wish I cold tell you more.

Barry