Hey Guys I read through some of your light bulb suggestion and tests threads. Didn't want to derail the other threads, so here goes.....
I am really surprised the consensus is that 2700K bulbs (CFL or perhaps general purpose LED) are better for algae growth than say 5100K bulbs!!!
I have been using a 5100K 23W CFL flood for my refugium, based on this site: http://www.melevsreef.com/fuge_bulb.html
where he tested the 5100K as being better for Chaetomorpha than 2700K. Was he mistaken somehow, or is macroalgae different than turf algae?
My situation: I failed to get an ATS scrubber going for various reasons, but have a macroalgae/pod refugium under the tank. Going to switch from the CFL to an LED, probably PAR30 or PAR38 size bulb. I thought the circa 5000K was a given......but found the suggestions here. My refugium is growing red algae Halymenia, and green Halimeda fairly well. The more directional and powerful light of the LED should crank them up I suppose.
Also looked into the LED grow lights, and sure enough, they are heavy on the red side. (Probably not at all good for my Halymenia). I am really surprised as I would somehow think that balanced daylight, equal red/blues (can lose the green of course), or else the noonday white 5000K (not the late day red shifted 2700K) would be better for Chlorophyll somehow. Anyone have an idea why heavy on the red would be better for green algae and plants?
Which brings me to another conundrum - why so far on the blue side for the coral tanks? Is it really beneficial, or do we just like it because of the oceanic blue look plus the fluorescence it causes? Maybe the coral would actually grow faster under 2700K bulbs, or even red/purple plant grow lights?
For the PAR38 type bulbs, I can get:
2700K
5500K
etc.
red/blue/purple grow light LEDs
10,000K/Actinic Blue LED bulbs for coral tanks (see marinedepot.com).
What is best for algae?