Corals lighting needs for survival.

Firstly corals that are sold to shops here in Auz come from coral leases in water temps from 28c down to 20c on average, there are no Auz coral leases close to the equator and its illegal to import corals-inverts to Auz, also the ocean is constantly under the influence of thermoclines,some of these go down to 13c and up to 28c at the same site.

This is why corals do best at temps around 24c in the aquarium.

Most corals collected also come from depths on average of 10 to 15 meters of water, this means that only 15 to 20 percent of the sun light reaches them and very little red colour getting to that depth.

In the eighties we surmised that even though the lighting we were using was no where near as powerful as the suns intensity, this we over came by leaving the lighting on for longer, I leave my lights on for never any less than 14 to 17 hours per 24 hour cycle over corals and 18 to 20 hours over algae.

This I had always believed and have done for some years and I remember quoting this to (a site) some time back and was ridiculed for such a silly thing,I assume this came from people that have not witnessed the ocean them selves over some years.

I came to the conclusion also that corals do not need UVR,it can actually harm corals and all resistance lighting has some UVR!

Some deeper waters corals, I put in the shallows with good quality waters and they would virtually all die, not around the edges or the coralline base that all hard corals use to attaché to the reef though, that part did quite well, the shallow corals taken deeper and left there, upon return some time later, were thriving, but not as cropped, they were a little more sparse in the community, more gaps!

I found, well I assumed that the deeper corals had not evolved the sun screening needed to protect it from the harmful radiation that is able to penetrate into the shallows and they died along the tops, and not slowly either, just in a matter of months!

High and low current areas were tried as well, chopping and changing corals there that gave interesting results as well!

Another thing i assumed is the reason corals exist at the greatest abundance in the shallows is their food source, plankton.

Phyto and cyano exists at the surface for its photosynthetic needs and the zoos come to this zone to feed on them, more so at night as many zoos hide in the reef until night, in the shallows you have the greatest abundance of food sources for corals and the algae clades have no choice but to be where their host is,lol.

As this article lends towards that there have been so many useless ideas over the years as to how corals live its not funny!

http://www.fishchannel.com/saltwater-aquariums/aquarium-frontiers/natural-reef-light.aspx