Glass/Plexiglass, does it make a differance?

[Doyu]

Hey all. I am a long time OG reader, I started my first grow less than a week before they were shut down and have been flying solo ever since. I just recently did some searching and came across what many seem to see as a refugee camp for OGers. I have missed the sense of community and free exchange of knowledge! Lets everyone !

I want to thank everyone that contributed to the design of my cab. I only wish I had paid closer attention hehe. Currently I'm on my 4th grow and have been struggling with heat problems since day 1 and I'm sick of trying to patch and bandaid the problem. So I'm rebuilding!!!

My question is in regards to air cooled hoods. I have looked around and I refuse to pay what the hydro stores want for something so simple. I plan to build one to fit my own space needs out of polished aluminum. I have worked with aluminum sheeting a little bit and I'm sure I can handle the reflector/bracket/duct flanges without a problem. My question has to do with the glass. I have spent several hours reading looking for an answer to this and there is some info but no direct comparison. The most common thing people seem to say is that glass (of any kind) will reduce UV light penetration and may effect yeilds. What I would like to know is if there is any significant differance between glass and plexiglass. Plexiglass is easy to cut and I can buy it at Home Depot so it would be the simple route. But if glass is better can anyone tell me how hard it is to cut glass? I know you can buy a $5 glass cutter at HD but I've never actually done it so I don't know.

I did have a 3rd idea that I could use the side or bottom of a glass aquarium. You could get 3 or 4 reflectors worth of glass out of one $12 10 gal. aquarium. But I dont know if aquarium glass can take the heat.

Any info or ideas are very much appreciated!

-Doyu

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Everything I say is a lie or copied from another source and is purely for entertainment.

 

[SomeGuy]

Get your glass cut to size by a pro. Its easy enough to do but if you mess it up its, get new glass and start over. Also the premade hoods come with tempered glass that shatters into tiny pieces like car glass. Much safer and it HAS to be cut by a pro before being tempered.

No experience with plexi in this situation but I would be concerned that the heat would affect it and it could sag over time and also it WILL develop scratches over time as you clean it. I have seen plexi turn milky after a few years of UV exposure but that was outside in direct sun.

That being said, you can probably get a tempered glass cut to size for around $20 or so and be done with it. Make sure you get it cut an 1/8 or so smaller than the actual size of the space you are trying to slide it into.

Good luck and stay safe!

 

[Doyu]

Thank you, you make a very good point about plexiglass that had not occured to me. I'm sure everyone can picture a boat or something with plexiglass that after a few years in the sun turns almost white and gets all cracked. I'm sure thats no good heh.

-Doyu

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Everything I say is a lie or copied from another source and is purely for entertainment.

 

[Underground Man]

It is cheap to get pieces of glass cut to any size, so make your hood whatever size you want. If you are in the US try Lowes. I wouldn't worry about getting tempered glass just don't punch your hand through it or subject it to temps more than a few hundred degrees heh. The thicker the glass the more light it will absorb.

 

[Guest]

ive used normal 1/8" glass in a 1200 watt hood for several years now, just dont get it wet....when its hot.

Most stores will cut the glass for you for free,if you buy it there,I know Ace hardware does.

I also put a strip of foil tape over my cut edges, but if you take the glass to a window installer, I think they can curve the edge for you, this helps stop the edges from chipping.

 

[Guest]

Regular glass would be the inexpensive route and should work fine although fixture manufacturers use tempered glass in most of their fixtures.I'm pretty sure tempered glass cant be cut like regular glass so you have to purchase it already sized.

 

[Pipedream]

Regular 1/8th inch glass will block about 8% of all transmitted light. But you hit the nail on the head when you said it blocks UV. In that spectrum, the percentage is more in the 45% area. These figures come right out of one of my ASHRE handbooks.

Optically ground and clear glass will drop both those numbers to the low single digits, but it is VERY EXPENSIVE. And, SomeGuy is right with what he said about Plexi.

If you are doing a small scale grow, you can place 1 or 2 CFL's below the glass to make up for the UV loss without generating too much additional heat.

If you look at this month's CC Magazine you'll see that Ed Rosenthal addresses just these issues.

 

[Doyu]

Thanks Pipedream. I had planned to put 1 or 2 CFLs in there anyway so I could shut the 400 watter and fans off without interrupting the light cycle...In case someone is to be in my basement and might come across the noisy windy cabinet hehe.

-Doyu

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Everything I say is a lie or copied from another source and is purely for entertainment.

 

[2buds]

Spend a few dollars and go tempered. When you find yourself spraying things or water splashing the tempered glass will be nice to have so its not shattering from water. If you can build your hood, thats great, most of us don't have the skills or tools to work metal so thumbs up man. Remember no matter how good your hood is you will still have some heat that radiates through the glass from the light but a sealed air cooled hood is night and day difference with heat issues. I would look at Pico's thread on light hoods and lumens http://www.icmag.com/ic/showthread.php?t=51325 , good informative info and may give you some great ideas on how best to design your hood. The tempered glass didn't reduce light output by much, just clean your glass regularly as dust, insects, condensation all dull things a bit. Good luck, post a pick of your work.

A side note, I think 1k bulb in a hood that say the fan quit working on with a plexiglass lens would melt the plexi, possibly pose a fire waiting to happen. A 1k bulb gets pretty dang hot. Anybody a got a laser thermometer that can get a reading off a 1k bulb burning bright?

 

[Guest]

Doyu, Plexiglass & acrylic isn't rigid like glass . Both will sag if not properly braced.Also either doesn't hold up to heat very well. It's a safe bet that the bottom glass panels on aquariums 20 gl on up are tempered .

 

[Guest]

I do,I'll go check now.I'm bliiiiiiind!!!It jumped around a bit but 520 degrees was the hottest steady reading I could get,it right on I'm sure I'm fuckin blind really

 

[Celticman]

Look into quartz glass.
http://www.newportglass.com/indgls.htm
If you want top notch specialty glass , this is a place to start.

Celticman