How far away from the bulb do acroporas thrive?

[tastingSalty]

I have a new 150w MH DE Phoenix 14K bulb in a lumenbright reflector with an icecap ballast.

How far do you guys think should my acroporas should be from the bulb?

I have them anywhere between 12" and 16" from the bulb right now and am running them on a 10 hour photoperiod.

I was thinking that I was giving them too much light, but I wanted to get all of your guys' feedback.

What do you think?

[Henry Bowman]

I'd shorten the photoperiod a bit. More than 8 hours with a good reflector and setup like yours is probably a waste of energy. The corals will produce all their daily requirements after 6-8 hours depending on placement in the tank etc...

[Frick]

<a href=showthread.php?s=&postid=15600520#post15600520 target=_blank>Originally posted</a> by Henry Bowman
I'd shorten the photoperiod a bit. More than 8 hours with a good reflector and setup like yours is probably a waste of energy. The corals will produce all their daily requirements after 6-8 hours depending on placement in the tank etc...

I'm not disagreeing with you, but I was always told 10 hours is ideal. Do you think you will get the same growth with 10 and 20 hours? Just something I always wondered.

[Reef Bass]

How long to run ones lights is a topic of great debate. Some people claim their corals are great with as little as 4 hours of lighting. Others say 12 hours. I like a longer photoperiod myself. I run my MHs 9 hours with 11 hours of actinics (an hour on each side of the MHs being on).

I personally can't see how photosynthetic organisms can do better with less light (assuming the light isn't too intense). The photoperiod near the equator where corals evolved is 12 hours, but obviously the intensity of light during those 12 hours is not equal.

[Frick]

Reef Bass that is a good thing to consider. I wonder if anyone has done reserch on growth related to light duration?

[ReefingMadness]

<a href=showthread.php?s=&postid=15603950#post15603950 target=_blank>Originally posted</a> by Frick
I wonder if anyone has done reserch on growth related to light duration?


If I am not mistaken, Sanjay Joshi has done the study. He spoke at our Frag Swap this year. I believe he stated that after about 6-7 hours of lighting, photoinhibition set in. Now that is with quality light, I don't know of any steadfast equation to balance out quality issues.

[reefer31]

I use 2-250 watt DE 10k ab bulbs. The bulbs were at 18" above the tank originally and on for 8 hours, I lowered them to to about 8 inches from the water to be able to use 20k bulbs but have not gotten them yet and shortened the light time to 6 hours. Some acros started to bleach near the surface and I decided to cut the hours to 4. All my sps are the same and have not declined in health at all. It sucks to have it only at 4 hours since I cant look at the tank for that long after work but its helped to get my acros to heal up and get used to the closeness of the bulbs. When I go 20k I will most likely push it back up to 8 hours but very slowly, bleached out acros look horrible :/.

[Henry Bowman]

<a href=showthread.php?s=&postid=15604488#post15604488 target=_blank>Originally posted</a> by ReefingMadness
If I am not mistaken, Sanjay Joshi has done the study. He spoke at our Frag Swap this year. I believe he stated that after about 6-7 hours of lighting, photoinhibition set in. Now that is with quality light, I don't know of any steadfast equation to balance out quality issues.

I wasn't sure where I read the information but what I do recall is exactly what R Madness is saying here.

I have a couple up to date reef books that I can look through to see if I have a credible resource to back up my earlier statement.
The discussion included the photoinhibition.

IIRC, there was also discussion regarding the corals feeding on other organisims (sp?) that were dependent or present due to light availability after the photoinhibition set in for the coral.

I.E. there's other stuff in the water for the coral to feed on through mechanical means due to light being present during the earlier and latter part of the day....make sense..?

[UC / Apsley]

Imo there are too many variables to conclude what ones photoperiod should be. Type of ballast, reflector, bulb, kelvin, height of lights off surface, etc. All come into play. I would say that one should look at there corals for the answer, if growth and colors are off than it's a good possibility that photoinhibition is occuring, if more than sufficent light is being provided. The colors and growth will tell you how long and how high off the surface your lights should be, granted some experimenting with those factors come into play.

[reefkeepa14]

there are always way too many variables, every system is different. deepth of tank, sps, or lps, water parameters, its finding what works for you. i personally run my MH 4 hours a day. i like to think of it like sunbathing. morning or evening hours the sun isnt too strong, so supplemental lightings runs all day. i blast my sps with MHs during peak hours of the day. like sunbathing it takes just a few hours of intense sun to cause a sunburn, and leave you with the effect of a sunburn the rest of the day. so for me, running my MHs during peak hours is all i need for the corals to thrive and take in what they need for the rest of the day. again, thats just me.....every system is different. go with what works best for you.