I am replacing my 55w actinics, at the moment i have 03 actinics and wondered about the 7100k actinics, will they make any difference to growth rates in the tank?
It probably wont make much difference. "Actinic" is actually a property of all light, and the 'actinic 03' name was really a marketing move by Phillips. In other words, the 'actinic' bulb that is best for your is the one you like the look of best. Personally, I like the O3's way better than the 7100's!
When you change the bulbs there is always a change in the coral that is using that light, but in this case I think it will make little difference.
I think this also depends greatly on the main source of light for the tank. Are you using MH? More VHOs? Just the PCs?
The 7100 is certainly a more 'white' look than actinics, but if you are using a different main light source, then the light added by those over 180g won't matter much.
