<a href=showthread.php?s=&postid=11665298#post11665298 target=_blank>Originally posted</a> by Kip
dark/drab acros usually have too much zoaxanthellae
longer photoperiod could keep some of those zoox faded and let the colors out
if not a lot of zoox and colors are bad due to poor nutrition... long photoperiod can bleach and starve the coral
all life forms need N and P... just not no3 and po4... it is a delicate balance that most stony keepers constantly battle
within the last few years... there have been tank keepers that run shorter photoperiods... like 4-6 hrs. i think this is all a function of how much "cleaner" (in fact, sometimes too clean IMO) we keep our systems than we used to (stronger skimmers, GFO, etc, etc)
<a href=showthread.php?s=&postid=11666839#post11666839 target=_blank>Originally posted</a> by x2uranium
On the equator does the sun not shine 12 hours per day?
<a href=showthread.php?s=&postid=11667037#post11667037 target=_blank>Originally posted</a> by jeffbrig
Conversely, do all corals grow within ~2' of the surface? Of course not, some corals can be found in as much as 200' of water or more. Obviously, these don't require 12 hours of high intensity light. How about a coral that occurs naturally at 60'? 20'? There's a lot more to the lighting question that replicating surface conditions at the equator. Also, remember that even though the day is 12 hours, peak irradiance is only a few hours around midday, very different from blazing 400w halides from sunup to sundown.
Personally, my lighting is spread across a 12hr photoperiod. T5 blue+ comes on first. An hour later, the T5 aquablues come on. That's my lighting combo for most of the day. I run a relatively short MH period, around 4 hours, to simulate midday sun. This is in an SPS dominated tank. Some of my acros had more color when I was running a 2hr MH period, others are more colorful with 4. Everything is a tradeoff, the goal is to find a happy medium for everything you keep.