Remove glass increase PAR?

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rodzilla420

New Member
I have a 1000W hps air cooled hood and read the glass does not let all the light get to my gilrs. Any harm removing it. I have a 6" fan pulling out one side exiting the room with other side open. Im thinking winter is coming and a little heat will be needed in room anyway. Oh i frilling love this site, did i ask my question? What was my question?
 
Yes, it is true that the lens on your reflector knocks down the available light. But only the less energetic light. This would be the light in the blue and ultraviolet spectrums. The amount depends on the quality and thickness of the lens.

As long as you can handle the heat... there is no issue in removing it. You will need to ensure that your plants are 24 to 36 inches away from the light though due to the extra heat and IR. Currently, I run my light within inches...
 
rodzilla420 said:
..... Oh i frilling love this site, did i ask my question? What was my question?
Click to expand...

Spontanious outburst of :love: for :420: FTW :cheer:




Take the glass away and set your photons free :)


Just keep checking your temps :thumb:


And maybe add a carbon filter where it blows out :ciao:
 
I wouldn't see a point in removing it other than a little more heat. It sounds like your setup is not sealed so your odor will still exit just as normal. If you were using a Metal Halide bulb then removing the glass would be beneficial as you get more UVB spectrum. Non of my hoods have glass on them, I'm all MH all through the cycle.
 
Hosebomber said:
Plain plate glass will not reduce any photons (disregarding the very small refraction amount, less than 0.00025%) above 320nm. The very large amount that would be reflected is actually the IR radiant heat above 860nm.
Click to expand...

Interesting.

In my study of optics, the best glass in the world with the best coatings will drop the light by 5%. The crappy binoculars that you purchase at Walmart are more like 20 to 25% loss.

It doesn't make sense to me to claim that there is no loss... when this is exactly what they fight in the world of optics.

I am assuming that the glass put into reflectors is nothing special... but that seems safe enough.

And I think we can assume that they are not using the best coatings and glass to build these reflectors... the best binoculars cost many 1,000s of US dollars.
 
Hosebomber said:
Plain plate glass will not reduce any photons (disregarding the very small refraction amount, less than 0.00025%) above 320nm. The very large amount that would be reflected is actually the IR radiant heat above 860nm.
Click to expand...


The "heat" from IR radiation comes from the absorption characteristics of the material which is "heated".

Photons are photons, regardless of their wavelength.

:peace:
 
Even Fused Quartz that they use to encase HID bulbs (fused silica)has some parasitic loss. And they use that for fiber optics.

But everytime you fire your ballast, lumens are decreasing in your bulb. So the bulb is not as bright on chop day as day one of flower. So you arereally mincing very fine hairs sir.
IMO a 2 year old 1000w bulb with glass will still be better than a 600w brand new no glass bulb. (only considering lumen production)
 
Just curious when you replace your bulbs. Mine have been running 12/12 for nearly 6 months and I swear they don't look as bright as they used to. I have read a year of useful life... but sometimes companies can be aggressive in their promises.
 
GreatLife4All said:
Just curious when you replace your bulbs. Mine have been running 12/12 for nearly 6 months and I swear they don't look as bright as they used to. I have read a year of useful life... but sometimes companies can be aggressive in their promises.
Click to expand...

Ive always heard when the cost of lost lumens > the cost of new bulb. But this is a crazy thing to estimate unless you grow the same strain and conditions so you can notice a definate loss in weight.

I dont have an HPS so I am not sure but I would assume every 3-4 grows?
 
Thanks... I believe I am going to get at least one new bulb.

The other tent is going to be used for an LED test... whole new light.
 
Great, you are referring to optical reflectors. The sheet of plain plate glass that is over the bottom of the reflective housing is just that, a plain sheet. It has no coatings and not focal distribution properties. Most of the photon loss that you get in reflectors and through refraction is not from the lenses. The cheap plastic LED lenses have a max of 7% lose and that is due to the absorption of UV photons. Glass will only absorb (and degrade) from UV A and B which is below 320nm. IR photons will be absorbed by nearly anything they come in contact with but I have yet to find a photoreceptor in the 850+nm range. So from that prospective the plant is not losing any photons that it would use in the growth or development process. As for the loss they are fighting in optics, that would be re-fractal loss. The amount of energy that is lost in radiant flux when the photon is bounced off of a reflective surface in an inverted direction more than one time before exiting the lens or entering the focal point. The only issue they have with glass in these cases is the speed at which the photon is traveling and not the number of photons.

As for the degradation of the bulbs, that is cause mostly by a burn-off of the gases in the bulb and dust and other particles in the air burning onto the bulb while it is on.
 
We will have to agree to disagree on the optics.

And in response to how much light is lost, I will post this: https://www.quartz.com/pxprop.pdf

There are several tables in there which show the light loss. It states that visible light loss thru the best Pyrex is 8% at 2mm thick. That would be about 1/10 of an inch. The lens on my reflector is much thicker than this. It is glass. It is made out of Pyrex if I am to believe the manufacturer.

Since my reflector glass is at least twice this thickness - let's call the loss 10%. As you can see from the chart - the loss in light which is available to the plant in the ultra-violet range is much greater than this.

So there is in fact a loss in PAR... something more than 10%... which is what the OP was about. On the website of the manufacturer of my reflector they state that there is "...no real loss in visible light..." - so I understand your position.

But... I would simply disagree with what the reflector manufacturer states on their web site... and so would the manufacturer of the glass that they are using.

If I have erred in my research, please feel free to correct me.
 
Pyrex is not plain plate glass. It is a composite formula developed to perform a specific function. In this case it is scientific glassware (beakers funnels flute etc.). There is no true photon lose when light passes through glass. It will change wavelength as it's speed is reduced but the thickness of glass for that to be noticeable is very large. If you would like to work out the equations, the following link gives the large majority of them in an easy to understand format: ENERGY OF PHOTON
 
I was hoping for a little more detail in all your answers. But riddle me this, by having one side of the hood open wasn't i already pulling in the sweet oder
 

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