Led grow light questions

KosarZiga

KosarZiga

Member
Hello.
I have a 4x4 grow tent. (first time indoor grow)

Till yesterday i had lumatek attis 300w led grow light. It was good for veg, but for flowering it has too small footprint. It's more suitable for 3x3.
So I upgraded to lumatek 600W pro.
It says its suitable for 5x5 grow tent.
Actualy it fits in my tent just barely :)

Now i need to figure it out on what height should i put the light and on how much power in %.

Recommended distance is around 12 inches..
At 12 inches i measured:
On 75% power i get around 38k lux
On 100% power i get around 51k lux

Recommendations from RQS are between 45 and 60k lux. But definitely not above 75k

I can achieve this lux by lowering the height.
I can get to 70k lux on 75% and 100%
On 75% you have to get few inches away to get 70k lux.
This means less energy consumption which is good.
But is it smart to place the light 3 inches away?

What would you guys recommend here?
Height and power consumption.. 20210302_205217.jpg

20210302_230418.png
 

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Eugenios

Eugenios

Well-Known Member
I would be looking at the ppfd map of this light instead of LUX. Or you can ask the manufacturers for recommended distance. Also, I don't know what you're measuring LUX with but if it's an app, I assume it won't be that precise. Peace.
 
Beehive

Beehive

Well-Known Member
Are we tracking that the LUX in veg is measured for 18/6?

Say, 27k lux in veg at 18 hours of light. Is the same amount of energy sent at the plant as 45k in flower. Measured at 12 hours.

Power increase happens as the plant grows. Starting at either 13.5k at dirt level. Or 15k. After a couple of weeks, past the 4th node. You increase lux. Working up to the maximum needed for veg. Maintaining about 2 feet of light height.


I have a plant that grew into 70k. Tall pheno that did it's own thing. The tippy tops are stressed but the lower buds get the perfect LUX. Overall, the tall plant will smoke excellent. The other plant has been at 47k the entire flower. Less stress but it'll smoke the same as the other.
 
Eugenios

Eugenios

Well-Known Member
KosarZiga said:
They are exactly 2 months old
On 12/12 for 2 weeks.
Isn't than better to lower the % of power consumption than lifting it up?
Click to expand...
I always have my light dimmed to 100% from the start of Week 3. I just adjust the distance according to which stage it's in and according to the ppfd map. Usually, 30inch distance for seedlings (dimmed), 20-24inch for veg, 16-18inch for flowering. That's with a Meijiu 240w QB.
 
KosarZiga

KosarZiga

Member
Beehive said:
Are we tracking that the LUX in veg is measured for 18/6?

Say, 27k lux in veg at 18 hours of light. Is the same amount of energy sent at the plant as 45k in flower. Measured at 12 hours.

Power increase happens as the plant grows. Starting at either 13.5k at dirt level. Or 15k. After a couple of weeks, past the 4th node. You increase lux. Working up to the maximum needed for veg. Maintaining about 2 feet of light height.


I have a plant that grew into 70k. Tall pheno that did it's own thing. The tippy tops are stressed but the lower buds get the perfect LUX. Overall, the tall plant will smoke excellent. The other plant has been at 47k the entire flower. Less stress but it'll smoke the same as the other.
Click to expand...
Thanks for your answer!
I didn't quite understand the last part.
You didn't see the difference between 70k lux and 47k lux?

You always maintain 2 feet distance?
 
LEDTonic - Daniel

LEDTonic - Daniel

Active Member
Seems like people got a bit off topic, although the info is valuable for sure.
To your question; if 3 inches from canopy is a good idea.

The lower your lamp is to your plants, the worse is the spread of light (as photons fall in a chaotic manner). While your bar-light naturally provides a good spread, you see from your PPFD maps the difference of light intensity in the corners at various heights. You see that the higher the lamp is from the plants, the higher the corner PPFD values are, i.e. the more light is directed to the corners.

I would keep the lamp at a minimum of 6" from the canopy, but the further away (without dipping too low on the lux in the middle, of course) the better corner light intensity and more uniform light foot print you'll see. So the question becomes: save money on electricity (by dimming it down) or go full power and raise the light to achieve a uniform light foot print?

I'd test the lamp at two heights, 6" and 12", and them measure the corner values with your lux meter. I'd aim for 20-25k lux in the corner (outer edges of your plants) and about 55-70k in the middle.
 
KosarZiga

KosarZiga

Member
LEDTonic - Daniel said:
Seems like people got a bit off topic, although the info is valuable for sure.
To your question; if 3 inches from canopy is a good idea.

The lower your lamp is to your plants, the worse is the spread of light (as photons fall in a chaotic manner). While your bar-light naturally provides a good spread, you see from your PPFD maps the difference of light intensity in the corners at various heights. You see that the higher the lamp is from the plants, the higher the corner PPFD values are, i.e. the more light is directed to the corners.

I would keep the lamp at a minimum of 6" from the canopy, but the further away (without dipping too low on the lux in the middle, of course) the better corner light intensity and more uniform light foot print you'll see. So the question becomes: save money on electricity (by dimming it down) or go full power and raise the light to achieve a uniform light foot print?

I'd test the lamp at two heights, 6" and 12", and them measure the corner values with your lux meter. I'd aim for 20-25k lux in the corner (outer edges of your plants) and about 55-70k in the middle.
Click to expand...
Hello.
Thanks for the answer.
I did the test.
On 6 points in the tent. 1 is in the middle, the rest are at the outer part.
20210309_080655.jpg

LUX measurement vary if you move the meter for an inch or so.. So the results must be taken with some error on plus or minus side.

I tested at 100% and 75% on the heights.
Results are in kLux (1000 lux)
image001.png

And at the end i tried to find the highest lux spot depending on distance. Again on 75% and 100%
11 to 12 inch really seems to be a sweet spot
image002.png

Any thoughts? :)
 
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