I agree with most of what you're saying but sps corals are found just below the surface of the ocean where the spectrum is actually 6,500k which is daylight white no 20,000k blue which is much deeper in the ocean.
Algae do not use green and yellow light for photosynthesis. Algae are plants and just like plants they reflect green light and do not use it for photosynthesis. Also, just so we are clear corals do not use light, it is the symbiotic algae living in their tissue that use light. So corals photosynthesize with the same spectrum as algae do which is where I agree with what you are saying. Corals utilities red and blue light the best for photosynthesis. So as long as you are running a large amount of blue and some red light your corals will photosynthesize.
A white bulb isn't white it is a mix of a bunch of different colors such as violet, blue, green, yellow, orange, red. I like to run a couple day light white bulbs in my mix because it helps keep the color of the corals and fish natural.
Hmm, so if I put all blue bulbs over my refugium, how does the algae react?
I understand and agree with you but just wondering why blue light won't keep algae if that is what algae uses.
I have also come to find that algae in corals is more of a hindrance. In my tanks, too much algae in a coral hinders growth a lot more than not enough algae. For good growth, it is all about food. Corals are animals, not plants. To treat them like plants is insane. They need real food to live and grow, not just light.
While there are quite a few SPS at the surface (15 feet or shallower) there are a lot of SPS colonies deeper down. Did you know that by 15 feet into water that red light is non-existent? By the time you hit 30 feet or so, there is a little green left but it is all blue wavelengths from that point on.
The majority of the coral reefs in the world are found in the 30-90 feet range. New discoveries may be changing this, as we find reefs 4,500 feet below water surface, but to my knowledge(which is pretty infant) most reefs are still below 30 feet of water.
White is a combination of red, blue and green. I think that daylight bulbs are important as well. I would never run a tank with all ATI Blue Plus or equivalent bulbs. You need a full spectrum lighting but I heavily weigh mine towards the blue, just how the ocean does.
The original poster wanted to know why I recommended only one or two white bulbs. I gave them my reason. I am not a scientist or even pretend to be. I just know what works in our tanks and try to share the knowledge. Thank you for pointing out the errors in my above statement. That is how I learn!
