ATP

How long should my metal halides for my 125 gallons be turned on?

harpua2002

If your corals are not used to the light, start at 4 hours a day and gradually increase the time the lights are on.

ATP

do I increase once a week? also when should I start it?

harpua2002

I think you're supposed to increase it by about one hour a week, but that's just what I've read and it's not something I have much experience with (I use HO T5s). I've seen it recommended so your corals won't bleach.

When you ask when to start it, do you mean what time of day? If so, I don't think it matters too much. Just sometime in the middle of the day and then gradually work up from there. I run my lights from about 12:30-9 for maximum viewing time while hubby and I are home.

ATP

Thanks

au01st

Photosynthetic corals get all the light they need in about 6 hours. This, along with a few other reasons, is why one way to run halides is 6 hours on, 6 off, repeating on a 24 hour period. Most people run them around 8 hours, with 9 being on the upper time period. However, if you want more tank viewing time you can run T5 or VHO actinic for an hour before and after the halides for a 10 hour cycle.

There's a few ways to acclimate corals. Start with a shorter photo period and the lights higher than you will have them. Extend the photo period 1 hour per week til you've reached the desired time, then start lowering the lights 2" per week to the desired height. If you don't have the room or means to raise/lower, you can block off some light with stacks of eggcrate and remove one layer a week til you get the light you want.