How far off the water should my lights be?

[Dargason]

A simple question... I'm building a hood for my 200 g system and I'm wondering how far away from the water my MH lights should be. Any ideas?

Thanks,
Mike

 

[Carpentersreef]

There are a few things to take into consideration. How protected are your bulbs from water being splashed on them?
Also, the closer the bulbs are to the surface of the water, the greater the heat from the bulbs will affect the water temperature, and you have to counteract that effect with appropriate cooling fans or a chiller. I've got 3 x 250w HQI MH suspended 8" over my open top 180, and the manufacturer recommends a minumum of 12". I use a 12" fan that blows over 50% of the tank, and that seems to keep the temp pretty much stable, even on hot days.
It's not a simple answer. Depends on the setup.

Mitch

 

[vp39]

Most every set up with MH's should be the inside top of canopy (or hood) at 14 inches from top of tank. This keeps heat from transfering easily to the tank. Most people also will add fans to the canopy also.
Glenn

 

[Dargason]

Thanks for the answers... that's basically what I was afraid of -- unfortunately lumber wider than 12 inches is expensive.

Maybe I'll have to use plywood.

 

[tetra]

Supposely MH is more intensed than PC. Would it defeat the purpose if it is too far away from the tank? Or, it is still better than PC at closer distant? Just curious, thanx.

 

[arnjer]

I used 1x12 pine. Made boxes with an open top and don't use fans and have 2x250 watts on a 90 gal and have no heat probs. I have pix of these and can send to anyone wanting ideas....the pix may take a while to download depending on your connection.

Jerry

 

[Dargason]

I'm not too worried about the heat -- my sump is in the basement where the temp never gets much above 70 degrees.

I think I might try the 1x12 pine...