Do I have too much light?

whoisami · Jul 5, 2020

Hi all. I am trying to become a more informed grower and understand how to maximize my yields. I am currently 3 weeks into the flowering stage of my first grow. I am growing in a 4ftx4ft tent with 3x 240w LM301h quantum boards with . I purchased a lux meter because I read about measuing lux to prevent providing too little or too much light for my girls. With my lights on full power I get about 75k lux at the top of the canopy in the middle and about 50k at the edges. I used an online lux to ppfd convertor (https://www.waveformlighting.com/horticulture/convert-lux-to-ppfd-online-calculator) and based on the calculator that is 1331.9 umols/s/ms2.

Here is where I get confused. I have read up to 85k lux can be okay for you plants. But, above 1000 umols/s/ms2 can be too much light and can burn the plants. So I am under the "maximum" lux but above "maximum" ppfd.

Can anyone help break this down and help me understand?

Thanks in advanced

LittleDabbie · Jul 5, 2020

Pics of the plant?

Aqua Man · Jul 5, 2020

whoisami said:
Hi all. I am trying to become a more informed grower and understand how to maximize my yields. I am currently 3 weeks into the flowering stage of my first grow. I am growing in a 4ftx4ft tent with 3x 240w LM301h quantum boards with . I purchased a lux meter because I read about measuing lux to prevent providing too little or too much light for my girls. With my lights on full power I get about 75k lux at the top of the canopy in the middle and about 50k at the edges. I used an online lux to ppfd convertor (https://www.waveformlighting.com/horticulture/convert-lux-to-ppfd-online-calculator) and based on the calculator that is 1331.9 umols/s/ms2.

Here is where I get confused. I have read up to 85k lux can be okay for you plants. But, above 1000 umols/s/ms2 can be too much light and can burn the plants. So I am under the "maximum" lux but above "maximum" ppfd.

Can anyone help break this down and help me understand?

Thanks in advanced

Imo without CO2 your not going to be able to run more than 65k and 45-65k would be ideal. I would say yes you are over lighting

LittleDabbie · Jul 5, 2020

Aqua Man said:
Imo without CO2 your not going to be able to run more than 65k and 45-65k would be ideal. I would say yes you are over lighting

Why does c02 allow you to run higher lux?

Aqua Man · Jul 5, 2020

LittleDabbie said:
Why does c02 allow you to run higher lux?

The increased CO2 allows photosynthesis to happen more efficiently... Otherwise the plants start going into photorespiration.

weedtech · Jul 5, 2020

This is a pretty good description of photorespiration:

Lecture 15

revfunk · Jul 5, 2020

Hmmmm

My buddy grows in a 4x4 with 4 240W lm301b boards and has great results! Lights as close as 6 inches sometimes later on in flower. Unless you are physically seeing light burn, there's no reason to place more distance between your light and the plants

Can check my thread too.....my 240W lm301b 3000k and 660nm quantum board is about 7 inches from a few of the tops

Aqua Man · Jul 5, 2020

bubblefunk said:
Hmmmm

My buddy grows in a 4x4 with 4 240W lm301b boards and has great results! Lights as close as 6 inches sometimes later on in flower. Unless you are physically seeing light burn, there's no reason to place more distance between your light and the plants

Can check my thread too.....my 240W lm301b 3000k and 660nm quantum board is about 7 inches from a few of the tops

And what's the lux at? And light cycle? Height of your buddies light.

I will say there is no way the are run at full intensity at even 18".

I run CO2 and can't run my hlg600 in a 4x4 at max granted I was pretty height limited

whoisami · Jul 5, 2020

LittleDabbie said:
Pics of the plant?

I can grab a photo later on. To me, the plants look relatively healthy, other than a single plant I am having some problems with.

weedtech · Jul 5, 2020

I would say YMMV and being stoned (alot) really widens the possible range. Folks have to dial in their own, based on their circumstances. To be fair - lamp types ( and age ) matter as well as spectrum. Lamps that are heavy in IR will bake yer babies.

whoisami · Jul 5, 2020

Aqua Man said:
Imo without CO2 your not going to be able to run more than 65k and 45-65k would be ideal. I would say yes you are over lighting

That is what I was thinking. I may back off a bit and shoot for around 55k lux as I dont use co2. I also read something about with the board dimmed a bit they run more efficiently. So maybe this is a good thing.

If you cannot run an hlg600 at max in the same size tent I would imagine I certainly should not be running x3 boards at max.

Aqua Man · Jul 5, 2020

whoisami said:
That is what I was thinking. I may back off a bit and shoot for around 55k lux as I dont use co2. I also read something about with the board dimmed a bit they run more efficiently. So maybe this is a good thing.

If you cannot run an hlg600 at max in the same size tent I would imagine I certainly should not be running x3 boards at max.

I can get the most 70-75k maybe a touch over. Anymore I see issues and I have done it more than a few times. Of course height plays a role if you have a higher room maybe max.. it's better to go by lux or par. Height for spread and intensity for just that

whoisami · Jul 5, 2020

Aqua Man said:
I can get the most 70-75k maybe a touch over. Anymore I see issues and I have done it more than a few times. Of course height plays a role if you have a higher room maybe max.. it's better to go by lux or par. Height for spread and intensity for just that

Great. Thanks. I will run around 55k-60k and see how I do. I appreciate all of the help everyone.

weedtech · Jul 5, 2020

My sense about this is that there aren't many farmers that get to spend lots of quality time making observations about the various impactful items. It often seems so simple when you start with outdoor farming. Indoors, its all on you.

So we see many folks that pound their seedlings with photons. And the beatings will continue until ....

In a good environment - you can see daily progress. If something is askew - its gonna take longer. This downside ( photorespiration ) is actually a big deal when you start using optimized photon guns ( LED ). The moral of this is that most life forms have a limit on "good things" they can use. Even humans (bags of mostly water) will die if they have too much water.

revfunk · Jul 6, 2020

Aqua Man said:
And what's the lux at? And light cycle? Height of your buddies light.

I will say there is no way the are run at full intensity at even 18".

I run CO2 and can't run my hlg600 in a 4x4 at max granted I was pretty height limited

75% intensity until final 2 weeks of flowering. Comes in around 70k at 75%.

Hell, one of my colas is 6 inches from one of those exact boards.....perfectly fine sitting at 90k lux. Obviously that's more than needed, I'm just saying it's more than possible my friend

Aqua Man · Jul 6, 2020

bubblefunk said:
75% intensity until final 2 weeks of flowering. Comes in around 70k at 75%.

Hell, one of my colas is 6 inches from one of those exact boards.....perfectly fine sitting at 90k lux. Obviously that's more than needed, I'm just saying it's more than possible my friend

If they are good then they are good my experience is different.

revfunk · Jul 6, 2020

Aqua Man said:
If they are good then they are good my experience is different.

I think 99% of the time it would be different bro, this cuts it awfully close to light burn

revfunk · Jul 6, 2020

Aqua Man said:
If they are good then they are good my experience is different.

Hold up.....no, it's 2 boards like mine but he has all 4 panels separate lmao so 2 lights not 4

Aqua Man · Jul 6, 2020

bubblefunk said:
Hold up.....no, it's 2 boards like mine but he has all 4 panels separate lmao so 2 lights not 4

Yeah that makes sense to me

sambapati · Jul 6, 2020

bubblefunk said:
75% intensity until final 2 weeks of flowering. Comes in around 70k at 75%.

Hell, one of my colas is 6 inches from one of those exact boards.....perfectly fine sitting at 90k lux. Obviously that's more than needed, I'm just saying it's more than possible my friend

The impossible just costs more $$$

Do I have too much light?

Do I have too much light?

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