Height and Wattage on QP's

I have tried scouring a lot of the different discussions on this topic, however I can not seem to formulate my own solid opinion yet as I am brand new to LED growing, and it may just be that the answer is there is no real answer and it is all in fact opinion and technique.

Do most use a single higher wattage panel at full strength and hang it higher above the canopy, or dim it down to drop the light lower? Or use multiple lower wattage panels for coverage purposes and put them lower down?

Let's say 3x3 flowering cabinet, four three gallon soil pots, and height not an issue.

Thanks!

Usually people build their fixture with a dimmer so they can keep the lights around 18-20"

Aolelon said:

Usually people build their fixture with a dimmer so they can keep the lights around 18-20"

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Thanks for the input. Could you run a 260W panel that close at full strength? Or would you need to dim it down?

For a 3x3 space, even with current tech diodes you're going to be a bit light of power/photons @260W. I'd shoot for a 320W driver and build from there.

PlantsAreNeat said:

I have tried scouring a lot of the different discussions on this topic, however I can not seem to formulate my own solid opinion yet as I am brand new to LED growing, and it may just be that the answer is there is no real answer and it is all in fact opinion and technique.

Do most use a single higher wattage panel at full strength and hang it higher above the canopy, or dim it down to drop the light lower? Or use multiple lower wattage panels for coverage purposes and put them lower down?

Let's say 3x3 flowering cabinet, four three gallon soil pots, and height not an issue.

Thanks!

Click to expand...

If we're talking QBs only, I would say it seems most people are running QB288s at full power (in flower, at least), around 18-24" from the canopy. Some (fewer) of us run the low diode-count boards, which can practically be slammed on the plants, even at full power. Different strokes.

If strips were in the conversation, I'd say that - like the low diode-count boards - they're more often slammed.

Get a cheap flux meter and measure your light output at canopy height. Dim according to your flux...

Be careful these leds are powerful, i had light burn thru most of my grow cause i had them cranked even at 16”. I’m still testing and learning

SMT69 said:

Get a cheap flux meter and measure your light output at canopy height. Dim according to your flux...

Be careful these leds are powerful, i had light burn thru most of my grow cause i had them cranked even at 16”. I’m still testing and learning

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18" or higher is recommended for QBs or PCB boards like these because they do create a pretty good hotspot up close. You can definitely have them closer than 18", but you need to keep an eye on them

Humple said:

If we're talking QBs only, I would say it seems most people are running QB288s at full power (in flower, at least), around 18-24" from the canopy. Some (fewer) of us run the low diode-count boards, which can practically be slammed on the plants, even at full power. Different strokes.

If strips were in the conversation, I'd say that - like the low diode-count boards - they're more often slammed.

Click to expand...

Clueless about these.. lol researching now.

With QB's stick to the height mentioned in the specs. Usually around 18". When you build something yourself from led strips you can go as low as 4"

It all depends on how many light sources you use. I use the distance between the light sources as a a maximum hanging height. So if you have one QB on a 2'x2' area, the max height would be 2'(24"). If you have a fixture with 4 strips on the same area, the max height would be 24" / 4=6".

I found that with strips you can even go as low as half that distance. So 3" minimum with 4 strips on a 2'x2' area. With COBs and QB's it seems you can drop to 2/3 of that maximum height. So 24" * 2/4 = 16". Close to what the manufacturer advises.

Difference with led strips is that they form a light line rather than a light point. So the strips can go a bit closer.

The reason this is such a simple equation is because they all have the same beam angle and therefore follow the same spread of light. The more you spread the lights, the more you need to increase the light to get the same uniformity of the lighting on the plants.

Benefit of having lights that can go closer is that you will have less wall losess.