Test room: DE HPS vs. Citizen COBs

a mongo frog

a mongo frog

Well-Known Member
verticalgrow said:
Just ask nevergoodnuf which side has the tightest buds :confused:
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Bro the cob side is beautiful i can see that. The cob side is also getting destroyed. Haven't you run DE before? Nothing is going to beat DE in that current set up. There is 6 pounds on that DE side, probably more. Tight as fuck buds too ask your boy.
 
nevergoodenuf

nevergoodenuf

Well-Known Member
Sorry everyone. Things have gotten so busy around here that I barely have time to look at RUI. At about week 3 things went down hill on the led side. This is exactly what would happen to me with Cutting Edge. The LED side got 3 units and the DE side got 4.5. So the LED side was .1 to 1.4 grams/watt behind. He will be around this whole run and will be trying to improve and catch any problems before they get worse. This run they were visually identical. I'm not sure how often I will be able to update, but I will try when I can.
 
thetr33man

thetr33man

Well-Known Member
Temps should never drop below 70 when you are growing LED, even during off period. Leaves curling means plants arent happy. Looks to me like hes got some nute and temp issues he needs to iron out of he wants to grow led.
 
kmog33

kmog33

Well-Known Member
visajoe1 said:
i havent ever seen a problem either. just curious what his reasoning was, we'll see if he responds
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Lights on LEDs should actually be quite a bit hotter than 70, but lights off doesn't matter for shit. Lights on leds need higher leaf temp than hid due to lack of ir / uv

Sent from my Nexus 5X using Tapatalk
 
Humanrob

Humanrob

Well-Known Member
I'm dealing with something similar right now with an experimental grow location I'm in the early stages of dialing in, and my 'lights on' temps stay between 68-74º under COBs. The seedlings don't mind it, but the clones I'm running are really hurting. I think there are multiple variables in play.

I read somewhere that cold temps make the plants metabolism slow down, and this causes what appear to be nute imbalances. It's not that the nutes are not available in the soil/medium, it's that the cold prevents the plant from up-taking them quickly enough to keep up with the leaves which are reacting to the intense light (I don't have a degree in botany, so my apologies if I butchered that explanation). Not a great solution for overall production, but I'm finding that since I can't raise my temps, its best for me to back my lights off until the temps warm up. I'll know more about this hypothesis in the coming days, the high for today outside is 55º, a week from now its supposed to be 91º, and in this grow space those outside temps will directly effect the temps inside the tent.

From what I've been hearing (mostly here on RIU), COBs are causing a lot of people problems that appear to be nute imbalances or pH issues, but I wonder if its equally (or concurrently) impacted by temps. Since they don't put off as much heat as HPS and there seems to be less of a heat stress/burn issue, its tempting to see how close we can get COBs to the plant. I'm thinking that the more intensely we run them, the more we need to keep the temps higher... of course, until its all just too much.


thetr33man said:
Temps should never drop below 70 when you are growing LED, even during off period. Leaves curling means plants arent happy. Looks to me like hes got some nute and temp issues he needs to iron out of he wants to grow led.
Click to expand...
kmog33 said:
Lights on LEDs should actually be quite a bit hotter than 70, but lights off doesn't matter for shit. Lights on leds need higher leaf temp than hid due to lack of ir / uv
Click to expand...
visajoe1 said:
i havent ever seen a problem either. just curious what his reasoning was, we'll see if he responds
Click to expand...
 
ttystikk

ttystikk

Well-Known Member
Humanrob said:
I'm dealing with something similar right now with an experimental grow location I'm in the early stages of dialing in, and my 'lights on' temps stay between 68-74º under COBs. The seedlings don't mind it, but the clones I'm running are really hurting. I think there are multiple variables in play.

I read somewhere that cold temps make the plants metabolism slow down, and this causes what appear to be nute imbalances. It's not that the nutes are not available in the soil/medium, it's that the cold prevents the plant from up-taking them quickly enough to keep up with the leaves which are reacting to the intense light (I don't have a degree in botany, so my apologies if I butchered that explanation). Not a great solution for overall production, but I'm finding that since I can't raise my temps, its best for me to back my lights off until the temps warm up. I'll know more about this hypothesis in the coming days, the high for today outside is 55º, a week from now its supposed to be 91º, and in this grow space those outside temps will directly effect the temps inside the tent.

From what I've been hearing (mostly here on RIU), COBs are causing a lot of people problems that appear to be nute imbalances or pH issues, but I wonder if its equally (or concurrently) impacted by temps. Since they don't put off as much heat as HPS and there seems to be less of a heat stress/burn issue, its tempting to see how close we can get COBs to the plant. I'm thinking that the more intensely we run them, the more we need to keep the temps higher... of course, until its all just too much.
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HID lighting has a lot of IR emission that keeps leaf temps up. Because LED doesn't emit nearly so much, higher temps really help. Think of it as an added benefit since this means you don't have to run the AC so hard!

I've found room temps in the low to mid 80s make for happy plants under modern LED lighting. That's as much as 10 degrees F warmer than under the old school light bulbs approach.

When running side by side comparisons, it becomes very important to take this temperature difference into consideration, otherwise the test results will be skewed. In other words, a true 'side by side' would place the plants in different spaces where temperatures could be better optimized for each lighting regime.
 
thetr33man

thetr33man

Well-Known Member
There are a few reasons. For one thing, unlike under HID, when leds turn on, they dont heat the leaves quickly, all the time spent 'warming' the room so that they can begin photosynthesizing is basically giving the HID a head start, every day. Even though the light is there, the plants cant use it because they are basically cold blooded, kinda like a snake or turtle, takes time to warm them up even after they get in the sun. The colder you allow the room to become, the more disadvantage you are handing to the LED plants, every day. You cant expect plants getting LED light to grow well in an environment that is not friendly toward them. Keep night temps above 70, allow ambient room temps when lights are on to hang around 80, not more than 85 but not less than 78 and give them some good 3000k 90 cri light and things would turn out much differently, IMO. Try doing another side by side keeping things LED friendly and see how the HPS likes it, probably not so much.
 
ttystikk

ttystikk

Well-Known Member
thetr33man said:
There are a few reasons. For one thing, unlike under HID, when leds turn on, they dont heat the leaves quickly, all the time spent 'warming' the room so that they can begin photosynthesizing is basically giving the HID a head start, every day. Even though the light is there, the plants cant use it because they are basically cold blooded, kinda like a snake or turtle, takes time to warm them up even after they get in the sun. The colder you allow the room to become, the more disadvantage you are handing to the LED plants, every day. You cant expect plants getting LED light to grow well in an environment that is not friendly toward them. Keep night temps above 70, allow ambient room temps when lights are on to hang around 80, not more than 85 but not less than 78 and give them some good 3000k 90 cri light and things would turn out much differently, IMO. Try doing another side by side keeping things LED friendly and see how the HPS likes it, probably not so much.
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There's increasing evidence that running nighttime temperatures the same as daytime or even somewhat WARMER actually boosts yields.

If so, this would play well to LED's inherent strengths.
 
Humanrob

Humanrob

Well-Known Member
ttystikk said:
There's increasing evidence that running nighttime temperatures the same as daytime or even somewhat WARMER actually boosts yields.
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I hope that's true, this summer I'll be running lights at night and daytime temps (lights off) will be at least as warm as (and probably warmer than) night time temps with the lights on.
 
ttystikk

ttystikk

Well-Known Member
Humanrob said:
I hope that's true, this summer I'll be running lights at night and daytime temps (lights off) will be at least as warm as (and probably warmer than) night time temps with the lights on.
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Some of my evidence comes from a neighbor; a soil science and conservation professor with 40 years in the field. He says it's not at all unusual for plants to grow at night as long as they have what they need, like water, nutrients and so on. Warm temperatures at night would be conducive to this, even accelerating growth over what would be expected with cool night time temperatures.
 
Yodaweed

Yodaweed

Well-Known Member
Good test , i noticed it was like 1650 watts (cob) vs 2600 watts (DE) i think if the wattage is more even we'd see more even results. I don't think the temps are that big of a factor , 2600w of DE is gonna always out yield 1600w of COBs.
 
CobKits

CobKits

Well-Known Member
ttystikk said:
When running side by side comparisons, it becomes very important to take this temperature difference into consideration, otherwise the test results will be skewed. In other words, a true 'side by side' would place the plants in different spaces where temperatures could be better optimized for each lighting regime.
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this

Yodaweed said:
I don't think the temps are that big of a factor ,
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its a major factor, leaf temperature for peak photosynthesis requires air temp in the mid to upper 80s with LED

LED side never had a chance in this test with the 4000k 70cri+ deficiencies+low leaf temps
 
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