Do you keep your LED's on 100% from start to finish, or change the strenght?

The topic `

I just heard someone saying the plants like it better when they get more light so i wanted to ask how you do it?

Also how high from the tops you keep your LED's? I got 4x 250w QB's in a 4x4x6 tent but haven't really "mastered" the height or power output despite trying different ones from suggestions all the way from 14" in flower to over 40" in veg..

I rarely will hit 100%. I use a par meter to dial it in. If you don’t have a lux/par meter I would just go off the manufacturers recommendation.

pahpah-cee said:

I rarely will hit 100%. I use a par meter to dial it in. If you don’t have a lux/par meter I would just go off the manufacturers recommendation.

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I only have a lux meter in my phone, so i don't know how far that is from reality. I have 4x 250w quantum bars in a 4x4x6 tent, i've looked a couple different recommendations from a single board: (aren't these recommendations measured with full power?)

Seedling: 60 cm (23")
Grow: 40-60 cm (16"x 23")
Flower: 30-40 cm (12"x16")

But would that change much with 4 boards covering the whole tent, and what do people personally would recommend to use if they have more knowledge?

I mean what kind of equipment people have, how much power they use in different stages of growing and how close from the canopy your lights are?

Those measurements are for full power. You can try to use that lux meter. Google how much lux to use for veg and flower.

1000watts is pretty intense in a 4x4. That’s 62.5 watts per sqft. That is almost double what some would recommended for that space.


what are the actual lights your using?

In my grows, full power seems to promote fox-tailing.

I ran my Grow Light Science Progrow320 full power for the 70 day flower run. GLS has a 120 return period so I ran it hot and hard to test it's reliability. VPD was too high during the LED stress test. I now have a Controller 69 Pro that dims the light when the tent reaches 80F. I limit the LED to UIS-8 = 240watts.

pahpah-cee said:

Those measurements are for full power. You can try to use that lux meter. Google how much lux to use for veg and flower.

1000watts is pretty intense in a 4x4. That’s 62.5 watts per sqft. That is almost double what some would recommended for that space.


what are the actual lights your using?

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I mean i have total of 500w, 4x 125w quantum boards from kingbrite

Blossom21 said:

I mean i have total of 500w, 4x 125w quantum boards from kingbrite

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500w will work great in that space. Just follow the manufacturer suggestions on height.

pahpah-cee said:

500w will work great in that space. Just follow the manufacturer suggestions on height.

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I can't find any manufacturer suggestions from the alibaba/kingbrite site for my exact lights because the order was custom with 4 quantum boards instead of having them attached together (with Samsung LM301B leds and meanwell drivers so they should be solid), maybe there's other products/manufacturers that make similar products and have tested them?

Well on the site i found two different suggestions on height and power from 2 different similar lights that were 480 watts, so how can i trust them?

You can’t really trust anyone’s opinion because everyone’s environment is slightly different.

I would give the less aggressive suggestion a try first. Then every so often you can up the power/lower the fixture. Pay close attention to your plant when you adjust it. If they seem like they’re getting stressed I would back off immediately.

Under 18/6 don’t need all that power cause of how many hours it’s getting light , under flower you give more light cause it’s 12/12 .. so in veg seedlings lowest setting and as they mature and get bigger you want to give more power up to 50-60 % … only time you go 100 % in lighting is when your in mid flower … I run a 250 watt in veg max 250 watt and only run it 3/4 strength at 30” away .

I'm using a watt meter along with tablet app that measures lux. I then translate that to a ppfd/umol reading using the spectrum that best matches my light. Oldest plant broke threw the soil 15,14 and 12 days ago. All seem pretty happy so far with a 100 watts of light. Slowly bumping up the watts each day or so. Max output is 330 watts which without co2 I'll likely never use all of.

https://www.waveformlighting.com/horticulture/convert-lux-to-ppfd-online-calculator

Depends, winter time when I want the extra warmth in the tent I run at 100% and raise or lower as needed. If I do dim it’s because there’s no room to raise it. I really ought to bite the bullet and get a par meter.

Greengrouch said:

Depends, winter time when I want the extra warmth in the tent I run at 100% and raise or lower as needed. If I do dim it’s because there’s no room to raise it. I really ought to bite the bullet and get a par meter.

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Another thing to shop for on black Friday!

I have a 4x4x7.5 tent and have been running Timber Daisies (5) for about (5) grows. They total 500 watts and I never run them full speed. If I do, it gets way too hot in the tent. I do not have Air Conditioning and my tent is running inside the NO AC house inside spare bedroom.
I use passive intake and an AC Infinity T6 inside the tent, but no outside fresh air.
If I had outside air or AC, I could possibly run them full blast but my I think my PAR would shoot through the roof and I would have to run them way up 24" and lose all that space. I run them minimum of 16" but mostly 18"-24". You should start higher and work down, usually your plants will tell you when they don't like it that close. Running mine at 18" and about 70% in San Diego gets me to about 80-85 degrees depending upon how hot it is here. The MFG says 18" -24" on these but as I shop I see almost all of them say about the same distance. only a few claim you can get closer like 8".

More light more nutes. The limit is pretty high

ILoveYourMom said:

More light more nutes. The limit is pretty high

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I should have mentioned I grow in earth boxes using living organic soil that I refresh and re-use. With that being said, I do not feed or add any nutrients until flip. At flip I stack a pile of compost and organic nutrients but not food. That may limit my ability to crank it up.

I change the strength of the light in one of my grow areas.
It's amazing how little watts/sq ft is actually needed for vegging. I find as long as they're getting the correct ppfd at the canopy all is well.

4 x 4 tent. My late veg, early flower area
It's in a cold garage. Tent is somewhat insulated.
Floor insulated.
Heatmat on floor.
12v 75mm pc extractor fan, need to keep some heat in there lol
I use an HLG 550R. I veg at lowest setting, around 220 watts. 400 - 500 ppfd. 24 hrs on.
The plants in the tent are now in flowering and are getting ~ 350 watts 800 - 900 ppfd. 12 hrs on.
Saves on electricity
I'd need to measure the height of light. Maybe 15"?
Now 28 days of 12 on 12 off




They will be moved to the main flower area on Monday when I've finished chopping the plants that are in there at moment.

Moflow said:

I change the strength of the light in one of my grow areas.
It's amazing how little watts/sq ft is actually needed for vegging. I find as long as they're getting the correct ppfd at the canopy all is well.

4 x 4 tent. My late veg, early flower area
It's in a cold garage. Tent is somewhat insulated.
Floor insulated.
Heatmat on floor.
12v 75mm pc extractor fan, need to keep some heat in there lol
I use an HLG 550R. I veg at lowest setting, around 220 watts. 400 - 500 ppfd. 24 hrs on.
The plants in the tent are now in flowering and are getting ~ 350 watts 800 - 900 ppfd. 12 hrs on.
Saves on electricity
I'd need to measure the height of light. Maybe 15"?
Now 28 days of 12 on 12 off

View attachment 5232984

View attachment 5232981
They will be moved to the main flower area on Monday when I've finished chopping the plants that are in there at moment.

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Nice looking grow!

Hey since you got similar kind of lights in terms of power, just a different manifacturer, could you tell how far you kept the lights starting from seedling? And can you only go down to 220w or what you mean? I can just turn the knobs from 0 to 100%, surely HLG would provide at least that.

Also can you just 24h during the entire veg state, what's the purpose of that since 18/6 seems to be the standard?

I just put seeds under a wet paper and waiting for them to pop. All feminised photoperiod seeds.

Blossom21 said:

Nice looking grow!

Hey since you got similar kind of lights in terms of power, just a different manifacturer, could you tell how far you kept the lights starting from seedling? And can you only go down to 220w or what you mean? I can just turn the knobs from 0 to 100%, surely HLG would provide at least that.

Also can you just 24h during the entire veg state, what's the purpose of that since 18/6 seems to be the standard?

I just put seeds under a wet paper and waiting for them to pop. All feminised photoperiod seeds.

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I don't use that area or light for seedlings, clones or early veg. I've other areas for that. I veg with 4 x 2ft Samsung F strips dimmed ~ 60 watts.
The 4 x 4 is the transitional area for aggressive vegging, early flowering. Those plants are now in the flowering hut.
It's complicatingly simple lol

The HLG has a Meanwell 'A' series driver so it has a built-in potentiometer screw accessed via a rubber grommet on top.
'A' drivers only usually dim to ~ 50%. I've always bought the Meanwell A drivers.

I veg 24 hrs on due to the cold temperatures I grow the plants in, it helps keep the temperature up a bit.
Just a bit less light over a longer period and it evens itself out.
Not much use when it's on 12 12 though, plants have to be tough in my gardens lol

Moflow said:

I don't use that area or light for seedlings, clones or early veg. I've other areas for that. I veg with 4 x 2ft Samsung F strips dimmed ~ 60 watts.
The 4 x 4 is the transitional area for aggressive vegging, early flowering. Those plants are now in the flowering hut.
It's complicatingly simple lol

The HLG has a Meanwell 'A' series driver so it has a built-in potentiometer screw accessed via a rubber grommet on top.
'A' drivers only usually dim to ~ 50%. I've always bought the Meanwell A drivers.

I veg 24 hrs on due to the cold temperatures I grow the plants in, it helps keep the temperature up a bit.
Just a bit less light over a longer period and it evens itself out.
Not much use when it's on 12 12 though, plants have to be tough in my gardens lol

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I have MeanWell HLG-240H-48AB drivers, nice when you can even tune it easily to meet your exact output just with a screwdriver, bonus if you own a multimeter so you can actually measure the output