Plexiglass heat shield?

I looked but didn't find much info on this. Does anyone have experience with using a plexiglass heat shield between their light and the plants?

If so...

The section of my closet in question is about 3 feet by 3 by 9 tall. At the top is a large carbon scrubber, and air is pumped in from two places; one at about 2 feet from the floor and one at about 4 feet. This section of the closet is fairly tightly sealed.

1) How much space (gap) should I leave between the edge of the plex and the closet wall, if any?

2) How many inches should there be between the plants and the plex, and the light and the plex?

3) How much would this cut down on the light from my 600 watt HPS, or is there a special "very clear" plexiglass that I should use?

4) What thickness should I use? I imagine that 1/4 inch should be plenty.

5) Should I drill any holes in the plex, or leave the two compartments mostly air-tight.

6) What are CO2 considerations for this? I have the stuff and intend to install it after a harvest fairly soon.

Thank You.

It kinda seems like you are trying to re-invent the wheel here. Why don't you get a cooled reflector? Many reflectors can be retrofit with kits available from the manufacturer.

...don't ya just hate it when people come up with lame-ass ideas instead of answering your damn question? LOL

PC :smokin:

I have a cooled reflector, If I understand the meaning of it correctly. It's a sealed hood around the bulb, over which air is pumped. Kinda like a cool tube. I still am getting temps a little higher than I would like around the plants, and I thought of this realatively simple fix. Guess I'll give it a try and experiment, if nobody has any ideas.

How about a reflector that actually has a refridgerant like freon in it?

plexiglass, glass, etc., will reduce lumens ... much better to just aim your oscillating fan over the space between the plants' canopy, and your lamp ... :smokin:

by the way, Opie, I built a bubble cloner like the one you showed here online, awhile back ... it works perfectly ! ... I have gone from 2% success rate :wtf:, to 100%, even with an experimental clone, taken from a Willie Nelson in her 7th week of flowering ! ... :thumbsup: .. that bubbler is great, thanks for the tips :D

Opie, I would shy away from plexi simply because I don't think it could take the heat.
'Real' (read: stuff you can buy lol) reflectors use tempered glass.

If you are already running an air-cooled reflector, you might try jacking up your air flow rate. When I was getting mine set up, I ended up having to use 2 inline fans to move air because the exhaust duct was 25 feet long and had a couple sharp bends. Just a thought.

Where is the air going when it leaves your hood? Are you exhausting it within the grow area, outside the grow area, outside the BUILDING...???

Yeah, I don't think it could take the heat. Plexiglass is some tough shit, some is even bullet proof, but its just like every other plastic.... when it gets hots, it melts. Real glass is inexpensive and not hard to get. And the glass store will cut it to whatever size or shape you want.

Thanks everybody for your advice.

Upon further review I think I will forget the plex or even glass for right now. I don't have an ocsilating fan blowing under the light because I thought the air being pumped in would suffice for that. I have a small fan, I guess I'll put that in there and see what happens.

the image reaper: very glad I could help. Of course the idea wasn't mine. I think I saw it on Overgrow when they were around. I just made a few changes. I see you are using peat pellets with the bubbler. I've never heard of that before, but I don't see any reason that can't work just as well, and obviously does. I've always set my clones directly in the cloner, without any medium to hold them. Once good roots are going on, I lay the roots right in dirt (in summer), water well and let dry out completely before next water. Obviously this works as well for hydro.

stinkyattic: I have two four inch inline fans (canfan brand I think) before my light, in a run of about 22 feet, with some corners. Zandor says you should have air pushed over your bulb instead of pulled, but I was thinking maybe it would be better if I had one of my fans after the light. Does that make any sense? My closet sucks air from near the floor of my office, and pushes it outside the building.

Hm, I was told by my grow shop fella that pulling air is more efficient.
I'd stick at least one fan after the light. Ideally, I'd put one RIGHT after the light and one RIGHT at the exhaust point. This isn't my most solid area of expertise though. It's just a gut instinct and the setup I am running on my 1000 atm except that I am running 6" fans/duct.

Yeah man - suck and blow.

Hahahahaha - "suck and blow" (chupe soplar) is a really, really hick Mexican name for a vacuum cleaner. For some reason I've always thought that was quite funny.

On a serious note - What kind of inline fans do you have? Are they moving some serious cfm or are they the little ones that are rated around 40 - 80cfm?

If you start using co2, your ventilation and cooling needs are going to change. If you find that you have to buy any new fans or such, you might want to get some info on co2 grows first, just to make sure you're not buying stuff you can't use later.

...but why listen to me when you can maybe find out from someone who actually knows what they're talking about.:D Check out this thread - down at the bottom is a post by Mississippi Steve. I think he started one or two threads of his own. I bet he could tell you everything you need to know.

Good luck :thumbsup:

PC :smokin:

Im planning to do this, but why plexi? use regular glass. Ace has sheets in the back that they will cut for you..

Mounting the glass tight to one side, where the fan will be, with a 2 inch gap on the other pulling air over the bulb

i just ran across this low e screen. it looks decent but i dont know it it takes away lumens.
ebay seller great lights 4 less
eBay: AIR COOLED Glass Lens 4 1000 400 600 hps MH Grow Light (item 260118514474 end time Aug-13-07 13:03:12 PDT)

Texas, cool link. If that really works like they say, I would like to replace my glass in my sealed hood.

I like how thay say that you will not need inline fans if you use their glass.
ha

i dont know i am thinkin bout tryin to get ahold of the company and ask the if they have more info on them,and ill try to post more
thanks

All the wonderful claims on that page are bogus. Think about it, even if the lens works as claimed, where is the heat going to go? It doesn't just cease to exist. Maybe it's momentarily on the other side of the glass, but it's still in the grow room unless/until it's extracted.

PC

Quote:

---

Originally Posted by stinkyattic

Opie, I would shy away from plexi simply because I don't think it could take the heat.
'Real' (read: stuff you can buy lol) reflectors use tempered glass.

---

Exactly what i was thinking.

If you're going to use anything at all, make it glass so it can take the heat. Not to mention glass cools off fast..

cheers,
Bob.

Quote:

---

Originally Posted by PharmaCan

All the wonderful claims on that page are bogus. Think about it, even if the lens works as claimed, where is the heat going to go? It doesn't just cease to exist. Maybe it's momentarily on the other side of the glass, but it's still in the grow room unless/until it's extracted.

PC

---

There are anti-detection and thermal resistant materials out there. If that's what you are claiming bogus. Even fire resistant materials out there that are used on space shuttles!

No bs!

Quote:

---

Originally Posted by BobBong

There are anti-detection and thermal resistant materials out there. If that's what you are claiming bogus. Even fire resistant materials out there that are used on space shuttles!

---

True, but I'm going to have to agree with PharmaCan that heat cannot cease to exist. Aren't those materials designed to just deflect heat? They are used on things that we don't want heat to get into, or someplace we don't want heat to get past. However it will just be dispersed to somewhere else. That would mean that all of the heat would still be in my grow space.

But wait, dad gum it. Now I'm confused. I think something like that may work in my case, at least in my sealed hood. If the glass deflected heat, it would be deflected back into the hood to be carried off through the cooling duct of the hood, assuming my fan is big enough to make any difference. In order for this to work, it assumes my fan could take on even more heat and get it out just as fast. I don't think so. Arrgh, new subject for now please.