Lighting

[Biocubehqi]

How long should I run my MH light for? My LFS said 5 to 6 hours would be plenty for my sps. Was I misinformed

[Michigan Mike]

You can run it a little longer if you want but I've seen awesome growth from powerful halides at the same length of time. If you have supplement lighting like actinics that's what I'd run before and after a strong burst from the halides.

[Biocubehqi]

I have a blue panorama led that I run before and after. All in all they equal to 12 hours I had the halide on for 9 to 10 hours and they said I may stress out my corals...

[Sugar Magnolia]

When I ran MH I did about 8-9 hours a day.

[Ron Reefman]

The accurate answer is, it depends.
How big and more importantly, how deep is your tank?
What wattage and color MH are you using?
How close to the water in the light?
What kind of corals do you have in the tank?
How long has this light been over the tank?
How long has the tank been under some other kind of light (if any)? And what was it?
Are you trying to just keep things alive or are you looking to make things grow?

You can get by with as little as 5 to 6 hours. Especially if the tank is a new set up, or the corals are zoas, palys and softies. Or if the water is shallow like a 12" deep frag tank or an 18" deep nano. Or if you just switched from some other light, like t5's or PC's.

If I ran my MH only 5 to 6 hours a day, I think my sps would suffer and my lps would stop growing. My lights start a 2 hour ramp up at 6am and run at various levels until the 2 hour run down that ends at 6pm. So my MH are between 50% and 100% on for 10 hours a day.

36ea 3w blue leds on at 6:00am
4ea 39w t5 actinics on at 6:30
2ea 250w 14K MH on at 7:00
2ea 250w 10K MH on at 7:30

leds and actinics off at 9:00am
250w 14K MH off at 11:00
250w 14K MH on at 2:00pm
leds and actinics on at 3:00

250w 10K MH off at 4:30pm
250w 14K MH off at 5:00
actinics off at 5:30
leds off at 6:00

[Biocubehqi]

Originally Posted by Ron Reefman

The accurate answer is, it depends.
How big and more importantly, how deep is your tank? we have a 29 gallon BioCube HQI,Dimension:
20"l x 20.75"w x 19.25"h (the actual depth from sand to top of water is 17in)
What wattage and color MH are you using?Lighting:
150 Watt, 14,000K, double-ended metal halide
How close to the water in the light?The light hangs about 6.5 inches above the water.
What kind of corals do you have in the tank?We currently have: button polyps, frogspawn, mushrooms, and a moon coral. We will be getting sps in the near future
How long has this light been over the tank?It's been there over 2 months
How long has the tank been under some other kind of light (if any)? And what was it?Since setup about 2 months ago, the metal halide. We were running it for about 11 hours a day. Were told to cut way back, could get by on 5 or 6 hours. So for the last week we have been running it for about 9 hours. We recently added a blue ecoxotic panorama pro led (12x445nm Royal Blue LEDs) light strip and have been running it before and after our halide turns on and off. Yesterday the cycle was : LEDs on 8am - 9am, halide 9am - 2:30pm, LEDs 2:30pm - 8pm. Today thinking of doing LEDs 9:30am - 10:30am, halides 10:30am - 4:30pm, LEDs 4:30pm - 9:30pm.
Are you trying to just keep things alive or are you looking to make things grow?
We are looking to make things grow. It's still a pretty new tank.


You can get by with as little as 5 to 6 hours. Especially if the tank is a new set up, or the corals are zoas, palys and softies. Or if the water is shallow like a 12" deep frag tank or an 18" deep nano. Or if you just switched from some other light, like t5's or PC's.

If I ran my MH only 5 to 6 hours a day, I think my sps would suffer and my lps would stop growing. My lights start a 2 hour ramp up at 6am and run at various levels until the 2 hour run down that ends at 6pm. So my MH are between 50% and 100% on for 10 hours a day.

36ea 3w blue leds on at 6:00am
4ea 39w t5 actinics on at 6:30
2ea 250w 14K MH on at 7:00
2ea 250w 10K MH on at 7:30

leds and actinics off at 9:00am
250w 14K MH off at 11:00
250w 14K MH on at 2:00pm
leds and actinics on at 3:00

250w 10K MH off at 4:30pm
250w 14K MH off at 5:00
actinics off at 5:30
leds off at 6:00

[Biocubehqi]

We recently added a blue ecoxotic panorama pro led (12x445nm Royal Blue LEDs) light strip and have been running it before and after our MH turns on and off.

Yesterday the cycle was : LEDs on 8am - 9am, halide 9am - 2:30pm, LEDs 2:30pm - 8:00pm Cut down to 5.5 hours

Today thinking of doing LEDs 9:30am - 10:30am, halides 10:30am - 4:30pm, LEDs 4:30pm - 9:30pm.So 6 hours of MH light today, will that be enough to keep our corals growing?

[Michigan Mike]

There is a guy on here who has some 400watt halides over his SPS and they have tremendous growth in just a couple months, he stated less hours was better under the intense halides and corals need to sleep too. He has them on for 5-6 hours if I remember correctly.
I also remember seeing a thing about corals using photosynthesis for around five hours or so before they start using less of the light energy and after that they dont hardly use the light you give them.
Think about it- how often in nature 24/7 365 does a plant or coral get direct light? Clouds,rain,seasons change ...etc
Average of 6-8 hours is a pretty good timeframe for good growth -I think.
Anyway do an experiment and see what works for you and your setup. Thats most likelythe best way to find out , if you never try anything different you will never know.
Using supplement lighting for viewing pleasure for the remainder hours is optimal for viewing if you want light for 12 hours. Running a longer photo period with under powered lighting is not gonna help growth either, you can't make up for under powered lights with more hours of light.