Changing a flowering room from HPS to LED

Hey guys and gals!

After my tent run with a COB LED really impressed me, I am seriously considering changing one of my flowering rooms to LED. It runs during the day and when it's 100 degrees outside the 4 ton AC has trouble keeping up. My high temp cutoff has to turn off the side lighting here and there to let the temps drop.

I did some math and if I went with Timber Redwood VS I would save about $225 a month on power just for the lights, not including the AC not having to work as hard. So about two years and they will pay for themselves.

I have my DE HPS lights mounted as high as they will go and I don't lower or raise them, it's not possible with my setup. My plants get massive and my trellis rig is 5 feet tall with 4 x 8 footprint for each row. I can't really even change a bulb after the plants are big.

Do you all think there would be any issue with using the COB LED's like I use my DE HPS? I don't wanna lose yields.

I would still have the HPS lights for side lighting and that would provide heat to keep leaf surface temps up.

Anyone see an issue with the plan to upgrade the lights? Think I can still pull the weight I am used to?

Should I just change one row and see how that does before doing all 3 rows?

The plants do get wider than the trellis rigs BTW, should I get the Fatty VS?

Plants are obviously huge but with all that space aren't you wasting a lot of light?

You should post this in the LED section, most of the very good LED and cob guys dont venture outside that sub section lol


id pack the room full of fattys

DaFreak said:

Plants are obviously huge but with all that space aren't you wasting a lot of light?

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Doesn't seem to wasteful when I am pulling 25 pounds out a room.

how many watts?

Never mind, I checked out your log, so about 1.1 gpw simplified. Certainly doesn't seem like you're wasting it but just knowing inverse-square law etc it still seems like there is a lot of space from the lights. Looking forward to see what you can do with the LEDs.

As to the waste of light, if you are talking about the walkways between the rows those actually provide more canopy area due to the sides. The extra light that doesn't hit the plants directly under a light helps light those sides and with a little extra side lighting they really put out nice big nugs.

Now there is a lot of light being wasted when the plants are small but the fact that it's there means the plants will spread out to get after it. Basically like a commercial grow where you have your lights up high and just light the whole warehouse. The light hitting the plants from all angles. So the light directly above the plant isn't the only light hitting the plant. Get the watts per sqft and grow some crop.

I look at energy as a throwaway. If it costs me 3000 or 6000 in power to grow a crop either way I am making money. I am only doing the conversion now because of summer heat issues in the daytime room. If I could use more watts even at a diminished return it is still profitable. So if I can add side lighting and get say a half a gram per watt boost it's still very profitable. I am trying to get as much as I can out of the room with various limitations such as my electric main is only 150 amps so I had to split my area and make two flowering rooms on a flip, plant count limitations used to be a big issue but I have a larger 74 count now instead of the 24 count I used to have.

We need numbers like your room size, to be able to figure this out...

Thing is, if you replace your HPS on a watt for watt basis you're going to end up with way too much light and a meager heat reduction.

Go led. It may be tough at first, but once you get it right, you will feel sorry for ever working with an HPS.

eyderbuddy said:

Thing is, if you replace your HPS on a watt for watt basis you're going to end up with way too much light and a meager heat reduction.

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Agreed, for example Timbers 1000 watt replacement uses like 640 or 650 watts, cant remember what one but after driver loss thats probably just a hair over 600 watts to the cobs. So with good LED lighting I would say you are looking at a 40% reduction in power consumption for lighting, thus equating to at least a 40% reduction in the need for cooling.

All in all I think a 40% reduction in heat from the main lighting source, estimating the DE HPS lights at 6k BTU/hr each, 36,000 BTU/hr or 3 tons total the reduction would be 14,400 BTU/hr. So a little over a ton less heat?

I can say that when my high temp cutoff kills the side lights I am probably fighting about 18,000 BTU/hr less heat and the AC is able to bring the room down to temp. Also the AC has no real problems in the winter or even when its only 70 outside. Only when the temps are 90 - 100+ outside does it fail to keep up.

Porky101 said:

Go led. It may be tough at first, but once you get it right, you will feel sorry for ever working with an HPS.

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Bro, did you even read my post? lol

Renfro said:

Agreed, for example Timbers 1000 watt replacement uses like 640 or 650 watts,

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Is the 640 or 650 watts replacing 1000 watts of DE HPS or, old 1000w single ended lighting?

I have a hell of a hard time believing that 650w replaces 1000w of DE.

But either way, if I were you i’d experiment with a row first or something. Then let me know how it goes please

I will let @RainDan answer that one but that is my understanding that it can replace a DE.

diggs99 said:

You should post this in the LED section, most of the very good LED and cob guys dont venture outside that sub section lol


id pack the room full of fattys

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That's not true I'm here lol

Aeroknow said:

Is the 640 or 650 watts replacing 1000 watts of DE HPS or, old 1000w single ended lighting?

I have a hell of a hard time believing that 650w replaces 1000w of DE.

But either way, if I were you i’d experiment with a row first or something. Then let me know how it goes please

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It will shit all over hps

REALSTYLES said:

It will shit all over hps

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Ok, so 3lb per 1000W DE fixture is 1.38 gpw. Pulling 3lbs from 650W of cob, or whatever it is you are saying will shit all over DE HPS lighting is 2.12 gpw.

So I understand you correctly, if I consistently pulled 3lbs from my DE fixtures, growing fire strains too, i should get at least that from 650W of a good LED fixture?

Aeroknow said:

Ok, so 3lb per 1000W DE fixture is 1.38 gpw. Pulling 3lbs from 650W of cob, or whatever it is you are saying will shit all over DE HPS lighting is 2.12 gpw.

So I understand you correctly, if I consistently pulled 3lbs from my DE fixtures, growing fire strains too, i should get at least that from 650W of a good LED fixture?

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4lbs is possible with a DE 1000(hopping for 2gpw next crop)
I’ve never seen an led match it, hear lots of talk, but no one can back it up.

BigHornBuds said:

4lbs is possible with a DE 1000(hopping for 2gpw next crop)
I’ve never seen an led match it, hear lots of talk, but no one can back it up.

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Hell yeah dude, that’s what i’m talking about!
I’ve hit higher than 3lb/light with DE’s, but I say 3 because I was consistently hitting that number with a few different flavors I was rockin, and I can only get away with growing the most fire possible here in norcal.
Even on Timbers website he recommends 900W’s of his COB led per 5’x5’. Ok, we get that with DE’s. More if you are in a grid.
Every comparison to hps lighting on his website says “traditional hps”.

I still don’t know anyone in real life who has a room full of LED’s only time I hear someone bragging that they kick ass are dudes that have just a couple of them.

I admit though, it took me a few months to believe what I was hearing about the numbers people were saying they were getting from DE’s before I sprung for some.

DE’s legitimately cut out 1/3 of the lighting watts needed for my grow rooms

Aeroknow said:

Hell yeah dude, that’s what i’m talking about!
I’ve hit higher than 3lb/light with DE’s, but I say 3 because I was consistently hitting that number with a few different flavors I was rockin, and I can only get away with growing the most fire possible here in norcal.
Even on Timbers website he recommends 900W’s of his COB led per 5’x5’. Ok, we get that with DE’s. More if you are in a grid.
Every comparison to hps lighting on his website says “traditional hps”.

I still don’t know anyone in real life who has a room full of LED’s only time I hear someone bragging that they kick ass are dudes that have just a couple of them.

I admit though, it took me a few months to believe what I was hearing about the numbers people were saying they were getting from DE’s before I sprung for some.

DE’s legitimately cut out 1/3 less lighting watts needed for my grow rooms

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DEs rock, I was consistently around 3 with them , switched to Phillips bulbs, n yields increased.
I also try to change bulbs after 2 runs .
I pay $120 all in pre bulb , (let’s say fire bud is $1600p) if I run the bulb 3 crops n my yield drops 1.5 oz I’m lossing in the big picture.

This is my 1st full run with this strain in my new setup, it stretched a lot more then anticipated, I stripped it so it would it put its energy into healing n bud sites , not vertical height. This is 15 days of 12/12



Different strain @ 6 weeks
It’s a solid cube of bud . This one I’m hopping to finally brake 2gpw .

Genetics is very important tho, I need the stretching n tight node spacing n a pheno that wants to make tight buds low.
Pheno hunting for your personal setup really helps up the numbers.

I don't know, I've used both HPS and LED's and both perform well.
I can say that replacing 750 watts of DE HPS with 570 watts of LED's bumped my yield up from 1.6 gpw under the HPS to 1.9 gpw under the LED with 8 sq, ft. less canopy area. Not to mention I no longer have to run my mini-split in my flower room.