Metal Halide Photo Period?

[Woodstock]

I honestly don't beleive that there are two reefers out there with the same MH photo period for their reefs! If you ask 10 different people how long to run MH over a reef, you will get 10 different answers! So do tell... how many hours per day do you burn your MH over your reef?

[Woodstock]

...remember.. this is ONLY for MH, not your supplemental actinics....

[Witfull]

9 hrs here, actinics 12hrs

[mps9506]

6 hours of 10k halides...

[Gina]

Right now we are running about 6 hours. On the old set up we ran about 9 hours.
We will increase the time when the corals adjust to the new tank.

[Woodstock]

What are the benefits of running the MH longer? Faster coral growth?

[Witfull]

in tropical waters the daylight photoperiod is near constant at appx 11+hrs. there is more of a flux in the GBR and Philippines. as you go more north or south the summer winter flux is a few hours. this is why people are using computer programs that follow the solar and lunar cycles to control their lights. similation of natural environment.

[Rougiem]

Originally Posted by Witfull

in tropical waters the daylight photoperiod is near constant at appx 11+hrs. there is more of a flux in the GBR and Philippines. as you go more north or south the summer winter flux is a few hours. this is why people are using computer programs that follow the solar and lunar cycles to control their lights. similation of natural environment.

I like that idea...When I go to MHs I will keep that in mind. Thanks Witty!

Cheers!

[Witfull]

you need to warm up the credit card there rodger, the equipment isnt cheap~~

[cheeks69]

I think the question is how long is it necessary to run the lights. I've reduced my photoperiod by 3.5 hours and my corals have actually improved their health since I was having serious problems with bleaching and STN.

[Woodstock]

Interesting Robert.. but that is for acclimating, correct? Are you planning to KEEP the photo period that short.

[cheeks69]

For part of the year I will, in the Summertime particularly since I was flirting with 86*F several times. I have noticed no Ill effects or slower coral growth and the Color of the Corals have actually improved. I read at RC a while back that all corals need is a couple of hours for photosynthesis don't know if it's true or not.

[Woodstock]

I've read about that also. Let us know how it goes for ya~

[mps9506]

I also noticed my tank seemed more stable overall when I reduced my photoperiod from 10 hours to 6 hours. I reduced the photoperiod slowly over about one month. My temps became more stable, SPS growth did not decrease.

Regarding the nearly 12 hour photoperiod in equitorial regions, this does not mean corals are exposed to 12 hours of direct sunlight every day all year around. Depeding on the location on the reef crest and taking into consideration the constant battle between corals to overgrow each other, most corals will not recieve a fulll blast of sunlight 12 hours a day.
There are also a few studies involving zooxanthalle energy production. There is only so much light they can feasibly absorb, and if you have 400 watt halides on above them, it is no where near 12 hours

[Woodstock]

Very true Mike. Do you run additional actinics? If so, for how long? FOr viewing purposes, I run 2 x 96 watt PC actinics for 12 hrs. I expect that these also provide some energy to the corals.