Two 175 watt MH bulbs over a 75 gallon tank.. how far up?

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greenmaji

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How far would you put them up off the water? providing there is plenty of active circulation (good fans).
just asking for an oppinion.. no right or wrong answers just wanting to get a few oppinons before I put them in.. thanks in advance..
 
I have two 175W MH over my 90 gal. The tank/hood/lights were given to me (I didn't design it) and the bulbs are about 8 inches from the water. I can measure when I get home. I have no cover, nothing between the bulbs and the water. Haven't had any problems. It will heat up the tank a bit without a good fan though.

I've read that if water hits the bulb when it's hot that it will shatter. I can speak from experience ( :oops: ) that it won't shatter.
 
the official instruction book that came with my lights said no less than 12 inches. I have really wanted to put them closer,but am afraid to do so.
 
My MH is about 10-12" above the tank water. I built a 12" tall enclosure for my 250W MH thats over the 20 gal tank. The enclosure sits down over the tank lip a little bit but the water level is also below the top frame a small amount. In the canopy I have a spider reflector with a mogel mount thats a few inches down from the inside of the enclosure.
 
my 250w MH are 12 inches from the the bottom of the bulb to the water. two 4" fans i can keep my temp where i want it. i think i could have gone closer to the water by a little bit

steve r
 
IMO, 175w do not produce nearly as much heat as 250w bulbs and are less likely to shatter. I keep my 2x175w on my 55g only about 4" off the surface, but this is because I am using the same canopy I had PC retros in. My new canopy will have them 6" off the surface and I will be comfortable with that amount of space. Even with 250's I'd not lose sleep if they were in the 8-10" range but would not push closer than that.
 
btw.. the ballasts are still in trasit and I still need to get reflectors, sockets, soket brackets and bulbs.. so I still have time to think about this.. thanks fokes.. :D
 
I saw a decent DIY article for aluminium sheet reflectors.. If I can find it I might give those a shot first.. doesnt everyone have a wish list though..
An EV180 is on mine.. LOL
 
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