GE 7500K flourescent bulbs emit more UV-A, is that good?

[stano]

I just picked up a GE Chroma 7500K 4' bulb today to try. I put it into my system and the light is pretty white compared to my other 50/50 and 10000K bulbs. I attached a pic for comparison. The question here is, has anybody tried these bulbs (which I understand are fairly new) in their reef tanks. I am upgrading to Metal Halide but an still planning a grow out tank which will use flourescents. I have a meter for measuring ultraviolet intensity/cm^2 (at 365nm) and found the output of a regular 50/50 bulb to be about 50 units and the Chroma 7500K to be 130 units. It appears to be emitting more UV-A light than my flourescents, which may or may not not be good. I know or am told at least that the 420nm peak is the best for corals. I am not sure what wavelengths this bulb emits, but it definitely emits UV-A. For comparison I measure daylight at 1600 units. Any comments? BTW the bulbs are 8$ compared to 30$ I am paying now...That is why I am bothering.

Stano

 

[Len]

A UV-A level that low is nothing to be concerned about. The energy will quickly be attenuated by the first few inches of the water. I wouldn't give it a second thought.

BTW, the efficacy of 420nm is dubious. It's proven that Choraphyll A uses this wavelength most effectively, but zooxanthalle employ more then just Choraphyll A for photosynthesis (B and caratenoids, for example). 420 "actinic" light is fine, but it's not the godsend that people used to believe it is.