safe minimum 250MH mounting height?

zachtos · 03/02/2011, 08:33 PM

Is it safe to mount a 250W SE MH w/ only 7" from canopy roof to water surface level? The bulb would likely be only 4" from the water that way, but I do not want to cut a hole in my nice oak canopy.

I would like to change the lighting on my 75G anemone tank out from T5 (4x36" on icecap @ 200 average PAR) to metal halides. Specifically, I would like to buy coralvue 250W e-ballast, reeflux 12K, spider/parabolic reflector and light the tank w/ only one bulb pointing down towards the anemone. I have a 240G SPS reef w/ the same thing but 400W x 3 in the other room. I do not want to exceed 250watts of heat because I know it doesnt overheat the tank in summer. I have a yellow tang, but have never seen him splash the surface like the angelfish in my 240G. I feel the anemone would benefit in coloration from more then 200 PAR. Hoping for double that at the bottom. If it dies, this will become my frag tank.

one used Icecap660 w/ SLR reflectors and 10-15 ATI brand bulbs will be sold on here to finance the switch.

dan-in-gr · 03/02/2011, 09:57 PM

Hi, you will want it higher, put some blocks under the hood or what ever method to raise it. having the bulb 4 inches from water is way to close and you will quickly heat the tank too high. My 250 bulbs are 7.5 inches from the water and I will be raising them about 1.5 inches higher soon. My 90 gal at current height with a 4 ft dual 250 with 4 T5's brings my tank from 78 to 82 at end of light cycle and I only run the MH bulbs 5.5 hours per day. Summer is coming soon and it will really heat up your tank, I am a chiller user, and you will probably want to get one also.

zachtos · 03/02/2011, 10:37 PM

Thanks, I have 500G water volume, so I doubt it will add too much heat, but good point. I will probably cut a hole in the top of the tank and set a pendant on top of the hole. Shouldn't look too bad, and will put the light 9" exactly from the water surface w/ no light spill... but an ugly hole in the hood. Sure hope I cut the hole right where I want it!

marius880 · 03/02/2011, 10:39 PM

wow.. i had the same question last night....

and i was looking for answers...

just tagging along... my lights are at 12 " above water and it floods the room with too much light... i want to lower them maybe at 10... i will follow what other say.. maybe its good enough, my sump is in the basement, so that might help me a bit with the heating part..

03/02/2011, 08:33 PM	#1
zachtos Registered Member Join Date: Dec 2003 Location: Milwaukee, WI Posts: 1,161	safe minimum 250MH mounting height? Is it safe to mount a 250W SE MH w/ only 7" from canopy roof to water surface level? The bulb would likely be only 4" from the water that way, but I do not want to cut a hole in my nice oak canopy. I would like to change the lighting on my 75G anemone tank out from T5 (4x36" on icecap @ 200 average PAR) to metal halides. Specifically, I would like to buy coralvue 250W e-ballast, reeflux 12K, spider/parabolic reflector and light the tank w/ only one bulb pointing down towards the anemone. I have a 240G SPS reef w/ the same thing but 400W x 3 in the other room. I do not want to exceed 250watts of heat because I know it doesnt overheat the tank in summer. I have a yellow tang, but have never seen him splash the surface like the angelfish in my 240G. I feel the anemone would benefit in coloration from more then 200 PAR. Hoping for double that at the bottom. If it dies, this will become my frag tank. one used Icecap660 w/ SLR reflectors and 10-15 ATI brand bulbs will be sold on here to finance the switch. __________________ 300G SPS reef build in progress Current Tank Info: 300G reef under construction

03/02/2011, 10:37 PM	#3
zachtos Registered Member Join Date: Dec 2003 Location: Milwaukee, WI Posts: 1,161	Thanks, I have 500G water volume, so I doubt it will add too much heat, but good point. I will probably cut a hole in the top of the tank and set a pendant on top of the hole. Shouldn't look too bad, and will put the light 9" exactly from the water surface w/ no light spill... but an ugly hole in the hood. Sure hope I cut the hole right where I want it! __________________ 300G SPS reef build in progress Current Tank Info: 300G reef under construction

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03/02/2011, 09:57 PM	#2
dan-in-gr Registered Member Join Date: Dec 2010 Posts: 385	Hi, you will want it higher, put some blocks under the hood or what ever method to raise it. having the bulb 4 inches from water is way to close and you will quickly heat the tank too high. My 250 bulbs are 7.5 inches from the water and I will be raising them about 1.5 inches higher soon. My 90 gal at current height with a 4 ft dual 250 with 4 T5's brings my tank from 78 to 82 at end of light cycle and I only run the MH bulbs 5.5 hours per day. Summer is coming soon and it will really heat up your tank, I am a chiller user, and you will probably want to get one also.

03/02/2011, 10:39 PM	#4
marius880 Moved On Join Date: Sep 2010 Location: lincolnwood il Posts: 525	wow.. i had the same question last night.... and i was looking for answers... just tagging along... my lights are at 12 " above water and it floods the room with too much light... i want to lower them maybe at 10... i will follow what other say.. maybe its good enough, my sump is in the basement, so that might help me a bit with the heating part..