Check out "inverse square law." Light energy diminishes over distance. I prefer white paint, not for the reflectivity but for cooler temps.
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150w HPS Club and Resource Guide......
- Thread starter Pipedream
- Start date
Check out "inverse square law." Light energy diminishes over distance. I prefer white paint, not for the reflectivity but for cooler temps.
yes i am familiar with it, but it only states that the energy of one point is this much lower further away. The total amount of energy is the same, it has just been spread over a larger surface(like blowing up a baloon: the walls are thinner when its blown up, but it still has the same mass all together). And when nearly all light is reflected to the plants, they will absorb the same amounts all together. And if I remember correctly, it is the leaves which do most of the photosynthesis for the plant, transporting the glucose to the buds through the stems. At least energy wise(amount of light being absorbed by the plant), there should be no difference as long as the the reflectivity of the walls is great enough(95%+) and no light energy is converted to heat. So unless the flowering tops induce some sort of chemical signalling from being subjected to very intense light, there is no logical reason to stress the distance. Or am i wrong?
I don't see this grower around much these days but he's got a pretty good explanation.
nice buds ruralroute420 - very nice - what was the total yield? you know you could run a 150 watt hps conversion bulb in there
vern and user_name - on the inverse square rule.... hmmm how best to put this - yes light intensity drops off as the inverse square of the distance - but it's not because the light "disappears" into the thin air or something, unlike glass the lumen loss due to travel through air is not appreciable over such short distances. The light intensity drops off because you are lighting a larger area as the lamp is moved up the light is spread out further making it less intense but over a larger area. the inverse square is based on the light being a cone, as the lamp is raised the area of the cone grows at a rate which increases by the radius squared. now we construct a traingle with one leg being the radius of the circle and the other being the distance to lamp. since we have a right triangle we can use pathagorian theorem to show that area being lit grows by the inverse square of the distance. Therefore since the intensity is lumens per surface area and the surface area is increasing the intensity at any one spot under the lamp will vary by the inverse square of the distance.
right now you're probably pissed I brought you back to geometry class... but here's the point.
the lumens being emitted by the lamp are the same - you are only spreading them out further when you move the lamp up further often times achieving better coverage
when growing in a cabinet and using reflective white walls or other reflective materials most of the light is striking the surface of your plant whether the lamp is 2" away or 10" away.
Look at pipedreams cabinet - or my cabinet - our lamps are permantly attached to the roof - not right down on the plants all the time.
anyways my .02 that's all
yes i am familiar with it, but it only states that the energy of one point is this much lower further away. The total amount of energy is the same, it has just been spread over a larger surface(like blowing up a baloon: the walls are thinner when its blown up, but it still has the same mass all together). And when nearly all light is reflected to the plants, they will absorb the same amounts all together. And if I remember correctly, it is the leaves which do most of the photosynthesis for the plant, transporting the glucose to the buds through the stems. At least energy wise(amount of light being absorbed by the plant), there should be no difference as long as the the reflectivity of the walls is great enough(95%+) and no light energy is converted to heat. So unless the flowering tops induce some sort of chemical signalling from being subjected to very intense light, there is no logical reason to stress the distance. Or am i wrong?
You are wrong. Light always behaves like a wave, even if it bounces off a wall, and that is the reason for the inverse square law... Or does a room covered in mirrors stay bright after you switch the lights off? ^^
You don't see it because you haven't actually studied it and don't understand it.
Try studying it and coming to an understanding, and you wouldn't have to ask why.
Or perhaps set up a test that only lets a plant see light the bounces from a white or highly reflective wall, and see what you get. It would prove your theory, yes?
But, I can tell you now that your thinking the energy is just going to be what it was when it gets there, is off. The light you can see is expended energy in itself.
See, not only do you need to take the inverse square law, but you need to also take into account the reflectivity of the wall. There are figures you can find for that part of the equation too, and if you do the math correctly using them, you will find the the light bouncing off the walls does what the math says it will do...very little no matter what.
Try studying it and coming to an understanding, and you wouldn't have to ask why.
Or perhaps set up a test that only lets a plant see light the bounces from a white or highly reflective wall, and see what you get. It would prove your theory, yes?
But, I can tell you now that your thinking the energy is just going to be what it was when it gets there, is off. The light you can see is expended energy in itself.
See, not only do you need to take the inverse square law, but you need to also take into account the reflectivity of the wall. There are figures you can find for that part of the equation too, and if you do the math correctly using them, you will find the the light bouncing off the walls does what the math says it will do...very little no matter what.
blwd67
Member
Don't know about the usability of reflected light, i do know that there is no way your reflective surface is 98%. Lab quality mirrors used with lasers are usually rated somewhere around 80-90%.
I have a basic understanding of light and it's physics but not enough to justify making myself look dumb in this thread.
So I put the 150 back up after a couple days 12/12 with just the cfls, they sucked and it was just really sad and pathetic looking. I broke the two large ones so I was under like maybe 100w of 6500k dominant.
Originally I had a piece of glass under the light to help with heat (can't swing the cool tube setup, it's crunch time, gotta pay for school). So today I found the glass broken under the light, luckily none fell on the plants. So bow I am wondering what the hell? I guess I knew that glass had temperature ranges, but I didn't kno that a HPS could get that hot. I am almost positive it was cracked from heat as they were like squiggly and the weight of the light was still held by the cab. The glass was originally a shelf, so it was pretty thick. Any ideas or suggestions?
I have a basic understanding of light and it's physics but not enough to justify making myself look dumb in this thread.
So I put the 150 back up after a couple days 12/12 with just the cfls, they sucked and it was just really sad and pathetic looking. I broke the two large ones so I was under like maybe 100w of 6500k dominant.
Originally I had a piece of glass under the light to help with heat (can't swing the cool tube setup, it's crunch time, gotta pay for school). So today I found the glass broken under the light, luckily none fell on the plants. So bow I am wondering what the hell? I guess I knew that glass had temperature ranges, but I didn't kno that a HPS could get that hot. I am almost positive it was cracked from heat as they were like squiggly and the weight of the light was still held by the cab. The glass was originally a shelf, so it was pretty thick. Any ideas or suggestions?
Thats pretty crazy blwd. I had a 400w MH bulb and reflector sitting directly on a sheet of glass from an old window (house window found in garbage area behind local glass shop took the glas sheet out left the wood...). The bulb would sit directly on the glass and it was thin and never cracked or anything.
blwd67
Member
Bueno dude I know I was like wha the fuck now I have to find a new piece of glass those exact dimensions to replace
The effing shelf... I would bet window glass would be like a higher grade. Also I was thinking that the piece I used may have been treated to be shatter proof? I k ow absolutely nothing about glass, but apparently don't use the kind I used.
Thanks for letting me know what's up bro, I've a couple extra storm windows in my basement and was wondering how they would hold up.
The effing shelf... I would bet window glass would be like a higher grade. Also I was thinking that the piece I used may have been treated to be shatter proof? I k ow absolutely nothing about glass, but apparently don't use the kind I used.
Thanks for letting me know what's up bro, I've a couple extra storm windows in my basement and was wondering how they would hold up.
Three things that are essential to the success of a small 150 box:
1. Air flow
2. Air flow
3. Air flow
No glass needed.
(buds that were in above shots...)
I'd suspect water quality. Defs aren't usually a problem with good nutes and the correct pH. BTW, what is it? With a deficiency, you usually have chlorosis before necrosis but your leaves seem to be going necrotic too fast for defs alone. Are you spraying anything on the leaves? Good nutes and proper pH might still see a deficiency if mixed improperly. Review your mixing process and make sure you're following the mfg's recommended order. I use floranova and that chit has to be shaken forever before mixing. If it's not shaken well it'll cause problems. GH Flora (micro) requires shaking too and should be mixed well before adding gro and bloom. Your nutes might have a specific requirement or it might be plug and play, just give it a double-check.
Get a couple gallons of spring or distilled water and see if your plants like it any better. I'd also consider filling out the form and posting a few pics in the infirmary. Lots of good help over there. Most likely, somebody will see your info and pics and know what's up.
You're right about PD's impressive hauls. Judging from the results, PD knows how to train plants as well as trim the undergrowth to maximize the canopy.
A 150 is good for about a foot of penetration. You might get a little more or less depending on your grow style, training and proximity to the bulb. PD has relatively ample headroom and enjoys some sexy, leggy girls. I tried the same thing with less than 3 feet of headroom and got this, lol! Not too sexy but you can see how the canopy is at the top and the lower stuff is culled.
On a side note, tempered glass is good for hoods or tubes if temps are a problem. A pc fan blowing on the hot spot might cool more effectively than glass. PD already mentioned there is less efficiency with glass in the equation, as much as 6 to 8% with "lamp" globes. Not sure how well thick shelf-glass compares.
But if glass helps remove heat, a potential pizza oven can grow hard bud. Even though the scrog dirt is only a foot beneath the lamp, heat isn't cooking the roots.
Here's a sog that takes advantage of the headroom. Even here the undergrowth is culled, in hopes the colas swell more. The roots are far enough away from the excess canopy heat to be nice and cool, making the tube unnecessary. But it also acts as an exhaust duct so I leave it in.
These two were allowed to spread. Even though there's some hard bud beneath, they're not as big. The yield was less because these plants weren't trained to fill the canopy-level area, even though the plants filled the "cubic" space of the cab.
In some cases, glass helps. In others a bare bulb might be more efficient, as long as the medium isn't almost as hot as the canopy.
Do you have a speed controller? I've got 95cfm turned down to the lowest setting and it's much quieter. A large closet might be easy to work with but a small one might have to be vented to keep temps down and air exchanged. It's your call on the pc grow as well.
blwd67
Member
Glass was so i could go ahead and use the 150 without having to spend money. I'll probably just not buy my history book or something and buy a new fan instead. A 'duct booster fan' would be something of interest for me? No allot of air to move in there so I don't need one of those crazy ass fans that's going to cost hundreds of dollars.
Lol, I'd get the history book. Too many revisionists abound and you'll benefit from knowing the difference, j/k. A booster might work if there's no filter to block air-flow.
. A booster might work if there's no filter to block air-flow.
The box I show above is exhausted with a 6" duct booster. $28 Home dePot.
I have a 4" fan ($6 Walmart) blowing directly at the lamp blowing the hot air into the duct booster and out. The box is not stealth, and there are no restrictions so the little fan works out fine.
If you need to run ducts, then the inline fans are going to be needed. Or, you can DIY a Lasko fan ($45 Walmart).
And I 100% agree with disco....GET THE HISTORY BOOK, and worry about growing pot later.
Seriously. Any time your grow jeopardizes your educational advancement, you are harvesting bad juju. You will probably agree with that more in time, but I highly suggest you hit the books now, and grow superior weed once you can actually afford such a hobby.
Many folks have ended up busted trying to cheap things out.
I have a 4" fan ($6 Walmart) blowing directly at the lamp blowing the hot air into the duct booster and out. The box is not stealth, and there are no restrictions so the little fan works out fine.
If you need to run ducts, then the inline fans are going to be needed. Or, you can DIY a Lasko fan ($45 Walmart).
And I 100% agree with disco....GET THE HISTORY BOOK, and worry about growing pot later.
Seriously. Any time your grow jeopardizes your educational advancement, you are harvesting bad juju. You will probably agree with that more in time, but I highly suggest you hit the books now, and grow superior weed once you can actually afford such a hobby.
Many folks have ended up busted trying to cheap things out.
Good to hear you do well in school, blwd67.
