How much light is lost through through glass lens?
- Thread starter clowntown
- Start date
good question...i don't think it would be enough to make a huge difference though, the only thing that worries me is a high wattage bulb gets very hot and a drop of water can make it explode, plus they are fairly easy to break when they are hot and you bump them with something, not to mention pretty spendy. thats why i always feel safer with the glass lens personally.....hope someone can answer you question though. peace
if i can remember from a physics book... i believe its about 8% light loss. But i do remember other growers saying that 10% is the amount...
BUT, thats nothing considering the benefits of a glass shielded aircooled reflector. Using an aircooled reflector allows us to bring the light closer to the plant without any heat damage. This allows greater penetration of light; thus the plants will utilize more light this way.
BUT, thats nothing considering the benefits of a glass shielded aircooled reflector. Using an aircooled reflector allows us to bring the light closer to the plant without any heat damage. This allows greater penetration of light; thus the plants will utilize more light this way.
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I agree...little loss..much needed to combat heat and protection of you and the bulb...The main thing is to keep the glass clean...Dirt,dust and pollen can block alot of lumens..If you lose 10% from just glass and your puttin out 150k lumens thats 15,000 lumens lost..If you lower the light 18" you gain 15,000 lumens (approx)....I thinks its something like 10,000 lumens per foot..So you break even...peace mitsu
What do you guys think about my triple-glass theory?
Sauce
Active member
I've heard 4% for heat treated poly carbonate and 6% for glass. I think pyrex will have a little higher of a loss but not sure. I've heard of up to 10% for glass.
Yes the triple glass theory is correct. Internal reflectors for a cool tube are more efficient. having both is probably best though.
Yes the triple glass theory is correct. Internal reflectors for a cool tube are more efficient. having both is probably best though.
Sauce
Active member
Alright was researching this a little after DurbanPoison linked me this sweet find:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=320019244689&ssPageName=STRK:MEWA:IT&ih=011
Up to 93% light transmission for Polymethyl methacrylate (acrylic), 90% (+/- 1) for polycarbonate, and 80-93% for glass (average 89%).
All numbers were from wikipedia or sources linked from wikipedia.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=320019244689&ssPageName=STRK:MEWA:IT&ih=011
Up to 93% light transmission for Polymethyl methacrylate (acrylic), 90% (+/- 1) for polycarbonate, and 80-93% for glass (average 89%).
All numbers were from wikipedia or sources linked from wikipedia.
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Thanks for passing along that information. Funny how the CoolMax is claiming only 5% loss (see first post)...
Off-topic, but BTW, that 11 7/8" piece would barely be enough for a small-wattage bulb like a 250w and not be too effective anything larger... right? And a larger piece that the guy is selling ... the 35 7/8", ends up costing enough where you can pretty much buy a Kool Tube from MD Hydro for $59 instead (with socket, wiring, reflector, aluminum ends).
Off-topic, but BTW, that 11 7/8" piece would barely be enough for a small-wattage bulb like a 250w and not be too effective anything larger... right? And a larger piece that the guy is selling ... the 35 7/8", ends up costing enough where you can pretty much buy a Kool Tube from MD Hydro for $59 instead (with socket, wiring, reflector, aluminum ends).
So on the triple-glass thing...
Without taking into account the amount lost on the reflection material and the extra distance traveled and assuming that all light is being passed through that triple-glass (which in reality is far from the case), and 10% loss through the transparent medium (glass): A 145,000 lumen bulb you would theorhetically end up with only 105,705 lumens as opposed to 130,500 lumens. Now that's about 27% loss!
Without taking into account the amount lost on the reflection material and the extra distance traveled and assuming that all light is being passed through that triple-glass (which in reality is far from the case), and 10% loss through the transparent medium (glass): A 145,000 lumen bulb you would theorhetically end up with only 105,705 lumens as opposed to 130,500 lumens. Now that's about 27% loss!
Sauce
Active member
That is true the plastic tube is a little short. Plus once you get the rest of the parts you would really only save like $20-30. I only have a 250w so I think it would work ok for me. I am still thinking about one of those mdhydro cool tubes though, can't beat that price.
Yeah the amount lost due to an external reflector is pretty substantial. However you must take into account that only about 1/2 the light (will vary) goes up to bounce off the reflector. So really it's about 1/2 of 27%.
Yeah the amount lost due to an external reflector is pretty substantial. However you must take into account that only about 1/2 the light (will vary) goes up to bounce off the reflector. So really it's about 1/2 of 27%.
Jorge Cervantes tested thoroughly all the major reflectors on the market and concluded that the cooltube was one of the worst in terms of reflecting capacity (batwing and diamond reflectors is the way to go in that sense). I've never seen that type of wing on a cooltube, perhaps it will improve things somewhat.
That 5% light loss figure is abstract. What's interesting is how many watts you put in and how many lux ends up on your plants. You have to enter your whole growroom setup as a factor in that calculation.
That 5% light loss figure is abstract. What's interesting is how many watts you put in and how many lux ends up on your plants. You have to enter your whole growroom setup as a factor in that calculation.
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