Bad News About LED vs HPS

BobCajun

Well-Known Member
What I'm trying now is HPS with a green reducing filter gel. HPS has way too much green/yellow. I'm using this 1/2 minus green type, made a half circle shape around the bottom of the bulb several inches away, with space all around it for air to go through by hanging it from it's corners with clear tape. No sign of melting. It's just a 150w.

What you find is that it looks dimmer, because less green is reflected from the plants, but when you stick your hand in you can feel the light energy is intense. Kind of like purple grow lights look dim. I also have a few LED "lightbulbs" in there to fill in some extra wattage. The plants are looking like they prefer it so far, only a few days. The filter does cut the light by about 30% though. Mine was too bright before anyway. Seems about right now. These gels are made for going on hot spotlights so it's not a big safety hazard or anything, as long as there's a few inches space from the bulb and it's not on top of it where most of the heat goes. Under the bulb, no issues.

Image from http://www.musson.com/sales/color-gels-filters/color-correction/minus-green/cinegel-3313-tough-1-2-minusgreen.html

 

BobCajun

Well-Known Member
I will indeed. I should point out though that the study used equal intensities, not equal wattages, so that's a factor.
 

InTheValley

Well-Known Member
You need greens for CO2 uptake, this is why HPS kickass with supplemental CO2. White LEDs look brighter, because they wavelengths pass THRU the leaves, which illuminate the under canopy.
 

chemphlegm

Well-Known Member
What I'm trying now is HPS with a green reducing filter gel. HPS has way too much green/yellow. I'm using this 1/2 minus green type, made a half circle shape around the bottom of the bulb several inches away, with space all around it for air to go through by hanging it from it's corners with clear tape. No sign of melting. It's just a 150w.

What you find is that it looks dimmer, because less green is reflected from the plants, but when you stick your hand in you can feel the light energy is intense. Kind of like purple grow lights look dim. I also have a few LED "lightbulbs" in there to fill in some extra wattage. The plants are looking like they prefer it so far, only a few days. The filter does cut the light by about 30% though. Mine was too bright before anyway. Seems about right now. These gels are made for going on hot spotlights so it's not a big safety hazard or anything, as long as there's a few inches space from the bulb and it's not on top of it where most of the heat goes. Under the bulb, no issues.
with cheap light meter you'll be able to go beyond terms like "looks dimmer","way too bright" - "looks about right"
and you wont have to guess how much usable light you pay for and how much of it you lose with a filter, not how "bright" it might be, but actually how much light energy is reaching your plants with and without. you could perform an experiment even without a plant, using a meter, just by holding up the filter for one second and looking at your meter. Consider the necessary UV you may be cancelling also.

A refractometer will tell you if your plant "like" your new experimental lighting or not by studying their metabolism and uptake. Better lights uptake faster, more efficiently, and leave little unburned, you could find that your filter may negate that process.

At 150watt the assumption of "too much yellow/green" is a moot point really. you have so much light penetration limit with that lamp I would be wary of letting even a clear piece of glass come between it and my plant.

have a blast!
 

ZeroTrousers

Well-Known Member
Okay, so we're missing some rather vital data from the set - what intensity (lumens, watts, PPFD) was used? what was the distance of each light to the plants?

most importantly, they selected one HPS (no bulb/ballast/brand info) and are comparing it to a KINDLED panel (outdated tech...) and an off-brand quantum board type setup that doesn't seem to use quite as many individual LEDs.
 

iHearAll

Well-Known Member
it seems like the results are so comparable that they mind as well be equivalent. i mean, the study is done on living organisms. Even if they were clones, the individual health of the plant at the bacteria level would make a difference. And, just because the individual would use the same exact nutrient formula wouldn't mean they have the same microorganism productivity. Id say, based on the graph, equal intensities of near same spectrums would in fact grow "equal" plants.
 

BobCajun

Well-Known Member
I appreciate your dedication to experimentation but it's hard to take anything you say serious after the curing thread and the BS toted there. Are you still toastIng your buds post harvest?
Yeah, toasting em up real nice. Who the hell smokes raw weed? Anyway I just wanted to bring that page to peoples' attention. Make of it what you will. I see it as bad news for LED supremacists. There's definitely something wrong with a light source if it always causes bleaching even at low intensity levels. I get noticeable bleaching with a 5 watter at about 8" distance.

HPS still have a place in the grow light world, especially when you sacrifice 1/3 of the power by filtering out half the green. Why? Because green is the enemy of vigorous plant growth if it's more than 25% of the spectrum. It actually inhibits growth. I do still use LEDs but not exclusively.
 
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BobCajun

Well-Known Member
It's a advertisement for someone selling lights.
Yeah I know, but you can just ignore the results for their lights entirely. Then it's just a study. Could contact them for more details. Maybe they'll tell you if you buy a light. They do look enticing, though probably cheap Epistars as usual.
 

ZeroTrousers

Well-Known Member
Yeah, toasting em up real nice. Who the hell smokes raw weed? Anyway I just wanted to bring that page to peoples' attention. Make of it what you will. I see it as bad news for LED supremacists. There's definitely something wrong with a light source if it always causes bleaching even at low intensity levels. I get noticeable bleaching with a 5 watter at about 8" distance.

HPS still have a place in the grow light world, especially when you sacrifice 1/3 of the power by filtering out half the green. Why? Because green is the enemy of vigorous plant growth if it's more than 25% of the spectrum. It actually inhibits growth. I do still use LEDs but not exclusively.
Bleaching with a 5w LED from 8 inches?

I've had plants within 6 inches of a Mars 300 panel (middle of the panel, a heck of a lot more than 5w of LED) with absolutely no bleaching. Heck, I have Pineapple Chunk that's trying its very best to reach out and touch my COBs - Vero 29 Gen7 D's at 80%. Even at 6 inches down, 2 inches off center it's only showing light stress, not bleaching. If i turned it up to 100%, that'd be a different story, sure, but still...

HPS hasn't *yet* been eclipsed by commercial LED, but that's just a matter of time. Every LED generation we see better photon flux/watt, the frequency discrimination gets better and the efficiency goes up. HPS certainly isn't dead yet, but it's not sitting securely on that throne.
 
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