What we need is some PAR measurements on a reef in Bali say logged hourly for a year, imported in to controller hooked up to a set of calibrated Sfiligoi dimmable MH lights.

This may be a stupid question, but should there be a time of total darkness? When my actinics and MH are off my moonrays are on which gives my tank light 24/7

Would the ocean be exposed to light 24/7? Probably not. A full moon only appears once every 28 days and even then you would have to expect some clouds to block some moonshine.

ya i know its young, and your more than welcome to come over and take a peak. after only a day and a bit I have noticed a big change in polyp extension in my tank. I purchased this branching sps last week and it has made the biggest change out of all the other ones in my tank. when it was at red coral polyps were fully out all the time. when i brought it home polyps haven't had the greatest extension like how it was at the store till now.

I will have to bump this thread in a month with updates. So far its working great

To play devils advocate, better polyp extension is not always necessarily a good thing. It could be a sign that the corals are starving :biggrin:

Don't you find that when you have more polyp extention it happens at a time when your corals are growing well and have their best color? When the polyps are retracted on a coral in my tank it's always when it's not happy.

Polyps on an sps coral are there to catch food, usually there is more food in the water at night which is why you get better night time extension. If a coral is hungry and/or if there is food in the water it extends polyps to maximize food catching potential.
A coral that wants to eat is healthy, a coral that needs to eat because it's not getting enough food from photosynthesizing is not

I was trying to simplify things.

Forget all the theories about what a coral needs or wants. Nobody really seems to know anyway... at least it's been debated to death.

I'm talking about when you're sitting in front of your tank, and you say to yourself "man, everything is looking sooo good now!" Your corals are growing like weeds, and the color hurts your eyes.

fuzzy sticks are healthy sticks... No?

Well I did say I was playing devils advocate and showing better polyp extension just because you have drastically cut back your photo period is not necessarily a sign of health

so true marie and i agree. its wierd though, some will have great polyp extension and others won't during the day. right now i am super interested how this turns out.

I agree and if that was the only "good" sign, I for one would never have cut back my photoperiod. But there is much more to it than good polyp extension.


I don't think anyone is arguing that this is the way to go or even the best way to light a tank. Its just yet another way that is working well for many. I know people with their halides on for 12 hours and by looking at the results (corals), you can't argue that they are wrong. Same way you can't say that TOTM I linked is not working out with his 6 hour photoperiod.

I'd love to see a chart of a PAR or lux reading taking on an hourly basis on a reef somewhere in the tropics just to see what the intensity curve really looks like.

Last time I checked the tropics were an even-Steven 12 hour day. To my Calgary eyes the intensity is all the same except for sun-up and sun-down. But the flip side is what is the difference between one million dollars and two million dollars? To a guy who has neither, they are both "wow that's a lot of money." But to someone else it may make a large difference. So that's why I say I'd love to see what a real reef encounters typically. Hey I'm all for a 6 hour halide day because I pay way too dang much for electricity per month and I need to find a way to reduce that .. but I want to be able to see my fish. I'm thinking maybe some supplemental T5's just to frame the actual intensity portion of the day.

Starting to hear enough anecdotal evidence to believe that the reduced photoperiod is onto something but on the flip side I wonder if people are a little too eager to jump on the conclusion bandwagon. Sorry, not trying to be harsh but the fad bandwagon can really be a little bit silly in this hobby at times .. :)

I don't know...for me the results people are getting are more valuable than any PAR reading really. IMO too many variables. For one, the sun over a reef in the tropics does not stay stuck at a high noon position for 12 hours like our lights do.

EDIT: Missed that you mentioned an hourly reading. This would be nice to see actually.

Again, I think it just all comes down to whats working for your tank. I have seen nothing but improvements after shortening the photoperiod. Perhaps the improvements in coral coloration and growth are a result of some other change or just an overall more stable system but I do know for sure that the improvement in my electric bill is the direct result of the lessened photoperiod--this is enough for me.

I say don't change whats working for you. If you are having great results at 10 hours, stay there. If you aren't liking the tank and want to try something new, try shortening the photoperiod. Nothing to loose really. Lots to gain if it works for your tank. My 6 hours a day bulbs will last much longer now than when I was running them 9-10 hours a day.