Glass for Grass light?

Greetings,
I have a small closet grow that is slowly taking over my life . I bought a used 250 watt MH and the closet is a little on the warm side (80's F). I have an 8 inch duct fan at the top of the room and this seems to help. I noticed that my hood (Hydrofarm I believe) has grooves where you can slide in a piece of glass.
Hmmmmmmm.
Should I go to the glass store and get a piece of tempered glass to fill this void? Is it necessary? Will this cut down on the lamps lumen output at all or just cut down on the heat? I am assuming I get clear glass. The hood has slotted vents on the sides not the circular opening I see on some. I don't really want to hook up my 8 inch duct fan to the light. I guess that's my main question, if it is a good idea to install the glass, is that all I have to do, or do I have to hook up a fan to it or something like that, as well??
Thanks in advance,
Z

The idea is to seal the light so you can draw hot air through one open duct and extract it out the other. The extraction vent is hooked up to dryer ducting and a fan extracting the air out of the top of the cabinet, into a carbon scrubber. This way, temps stay down and your room doesn't smell like a Jamacian Ganja Factory. *lol*

Oh, and to answer your other question: Clear glass won't cut down on lumens. Just clean the glass between grows.


Vi

Listen to Vi.

Those hoods with just the vents on the sides would be tough to air-cool. You'd have to attach a round flange to connect ducting to, and it wouldn't work very well. And without the air moving thru the hood, I would not put the glass there. I would think that the heat would build up too much because MH are even hotter than HPS, and then you'll have an even bigger and hotter oven in your closet.

Is your duct fan exhausting the air? It should be, and since you have that, you should just change to an air-cooled hood, and exhaust thru the hood.

All problems solved.

first off for a 250w you do not need tempered glass. They do not cut tempered glass so it would have to be custom ordered, and more expensive. You may have a flange for a 4" vent on the hydrofarm hood. Go with a 4 inch fan. Aircooling a 250w is kind of pointless in the end unless you are getting some kill results

Zitngrow said:

Greetings,
I have a small closet grow that is slowly taking over my life . I bought a used 250 watt MH and the closet is a little on the warm side (80's F). I have an 8 inch duct fan at the top of the room and this seems to help. I noticed that my hood (Hydrofarm I believe) has grooves where you can slide in a piece of glass.
Hmmmmmmm.
Should I go to the glass store and get a piece of tempered glass to fill this void? Is it necessary? Will this cut down on the lamps lumen output at all or just cut down on the heat? I am assuming I get clear glass. The hood has slotted vents on the sides not the circular opening I see on some. I don't really want to hook up my 8 inch duct fan to the light. I guess that's my main question, if it is a good idea to install the glass, is that all I have to do, or do I have to hook up a fan to it or something like that, as well??
Thanks in advance,
Z

Click to expand...

Several years ago I picked up a used 400w MH light fixture that had a hood/enclosure that sounds much like yours. It was adding way too much heat to my grow space (especially in the summer). I modfied it to have it's own forced air cooling system that was seperate from the rooms ventilation so that it didn't suck out the CO2 I was adding to the space.

I got everything I needed to do this at Home Depot for less than $50. The parts included 2 4" starting collars, 12' of flexible drier ducting and a 4" inline duct fan. I vented mine to the attic and for ceiling penetrations I used 2 toilet mounting flanges and 2 18" pieces of 4" pvc pipe.

I then used that foil duct tape to seal up all those side vents (and the corners) on the metal hood. I've got the 4" duct fan wired in to the same timer that controls the light so that when ever the light comes on it starts blowing air thru the light fixture.

I've got a seperate ventilation system for the room air (the best bathroom "fart fan" I could find at Home Depot, $110) that exhausts thru a homemade carbon filter (also sitting in the attic). I've got this controlled by a seperate timer that I set to run according to what time of year it is and how hot or cold the space is.

For instance, over the summer it came on for 15 minutes every 2 hours. I had it synced up with the CO2 timer so that as soon as it shut off the room got a fresh squirt of CO2.

The whole thing takes a little bit of playing with to adjust to the changing seasons but hey, that's part of the fun of it for me. Where I'm at the out door temps can run from 100 in the summer to -40 in the winter. All though I get the occasional high or low spike I seem to be able to keep the room temp between 70 to 80 with out to much trouble.

In the winter I have to use a small electrical space heater (WallMart $25) to keep the night time (lights off) temp from getting to low.

If you're light has a seperate ballast (as mine does) I would recommend that you move it out of the grow space (since you seem to have trouble with excessive heat). Mine sits up in the attic during the summer and gets moved back into the space during the winter.

If I were you I would get a piece of glass for my light hood and then modify it with it's own cooling system. If you're not using CO2 (or planning to) you could just suck the room air in thru those vents on the side of the hood and exhaust it thru the vent fan you already have. I should think that would help make a couple of degrees difference (and help your bulb run cooler).

I don't know how mechanically inclined you are but it is possible to put a nice hole for a venting connection in the light hood using a drill and a 4" hole saw. The trick is to keep it backed up with a piece of wood while you do it.