Hood building DIY

[Clown Monarch]

I've just ordered a 250w MH retro kit and am about to build a hood for a 44 gallon pentagon. The MH will fit nicely with 2 small actinic mini-hoods and a couple fans under there.

Does anyone have any suggestions for the building process? My considerations are:

1. Moisture. The last hood I built of wood was fine over FW, but has warped badly over SW. I was thinking of a few coats of urethane under the hood, then "wallpaper" the inside with aluminum foil. Does this sound like a plan?

2. Heat. A decent amount of heat built up under my previous DIY hood even with only 60w of NO lighting. I'm upgrading to 250w. How much heat will I need to move and how tall should I build the hood?

3. Fire Hazard. As if a giant plate-glass box filled with hundreds of pounds of water surrounded by 500w of electricity isn't enough of a hazard, I'm now adding high heat and wood to the mix. Is there any precautions I should take in mounting the MH fixture to the top of the wood hood? Possibly some kind of buffer between them?


Any comments from DIYers' are appreciated.

 

[Biggen]

Moisture. The last hood I built of wood was fine over FW, but has warped badly over SW. I was thinking of a few coats of urethane under the hood, then "wallpaper" the inside with aluminum foil. Does this sound like a plan?

Not too sure on this one as I don't have this problem. Then again, mine hangs about 10 inches over my tank so moisture can't get trapped. I would imagine urethane would seal and waterproof the wood so this doesn't happen, however. Adequate ventilation around the canopy would also remove the buildup of moisture.

2. Heat. A decent amount of heat built up under my previous DIY hood even with only 60w of NO lighting. I'm upgrading to 250w. How much heat will I need to move and how tall should I build the hood?

I left 1/2" gaps between my wood slats that I used to make the top of the hood. This allows natural convection to take place. As the warm air rises out the top, it creates negative pressure which pulls in cold air from the bottom. I also installed two 4" fans on each side of the canopy. One sucks air into the hood while the other blows it out. I have zero heat problems with this setup.

3. Fire Hazard. As if a giant plate-glass box filled with hundreds of pounds of water surrounded by 500w of electricity isn't enough of a hazard, I'm now adding high heat and wood to the mix. Is there any precautions I should take in mounting the MH fixture to the top of the wood hood? Possibly some kind of buffer between them?

Again, since mine hangs over my tank, I didn't have to deal with this issue. So long as it is sturdy and doesn't fall into the water, you will be fine. Just make sure your lights are a minimum of 6" off the surface of the water. Mine actually sits 10" because I wanted a larger margin of error. You might also want to think about remotely mounted the MH ballast. This will cut down on the weight of the canopy as well as the heat.

 

[Clown Monarch]

Good advice - thank you.