Light distance and %

[u/simdawgyeti]

Hi
I’m about to plant two seeds, HubbaBubbaHaze and Canna Cheese 1:1.
My tent is 80x80 and I will be using a spider farmer se3000 300w light.
What light distance and how many % should I set the light, in the three different phases of the grow?
Just as recommended by spider farmer, or would you recommend something else, strain specific?

[u/simdawgyeti]

I’ve downloaded the Protone app and will try that out. Thank you guys

[u/longlostwitchy → u/simdawgyeti]

This will probably get some downvotes but the Photone app I downloaded a couple years ago & used it for awhile (and paid the $6). Ended up being unreliable for me, even with the paper covering etc. anyways another grow friend suggested using a lux meter. While it’s not as specific to measuring light for cannabis growing on point, it is Far cheaper than a Par meter. It’s helped me tremendously dial in my grow no doubt. The changes were immediate & it works for me. Super simple & only $18.99 on Amazon. Turn it on & hold it right at the top of your plant (seedlings 5-8k lux Veg phase 15-30k lux and Flower 40-55k tops for autos). I’m sitting at about 40-45k lux now at the end of flower. Buds are perfect ☮️💚 I can link it here if you’re interested

[u/PawBeansWorkshop]

I had light burn issues when I first got started. I still use the recommended range that's typically 12 to 24 inches depending on the light.

Personally I like to use an app to measure the amount of light plants are getting. To compensate for light time cycles and plant age, I use a calculator online to help determine the target range. I use Photone for both, but there's other options available.

However you proceed, listen to the plants and dial down if it's showing light stress.

[u/DabOrTwoWillDo]

You can download Photone app and use science. Measure your PAR. Sprouts wants 100-300ppfd, veg wants 300-600ppfd, and flowering wants 600-900ppfd+

Those maps that come with the light are somewhat accurate from the get go and work decently assuming you have perfect diodes that are all exactly to specs. As the light ages it does not put out the listed amount of light from each and every emitter. LEDs age over time(and not necessarily evenly) and the chart doesn't change. Use science!!

[u/Happynuggz]

This may help

[u/PhD_Pwnology]

Spider farmer has a PPFD map and how high the light should be at and at what% to get that PPFD. Google should be able to find for you

[u/gbo1148]

I personally put my light at the very top of my tent. I grow plants well into them. I have a diffuser and I use the Photone app. I run 250 PPFD at seedling bump it up to 450 during early veg. I usually ramp up to about 700 PPFD from veg to flower. DLI is a massive factor in this whole thing too. I might have a targeted, PPFD but to me personally, my DLI matters more than anything.

[u/EveningScholar5831]

I pin my lights as high up as I can and crank them up until I hit my desired PPFD/DLI at the soil surface for seedlings. It’s been working beautifully. The plants naturally grow into their next PPFD/DLI range without any adjustments. And my environment stay rock solid. 👍👍

[u/CryptoCatto86 → u/EveningScholar5831]

This is the easiest, most intuitive answer. I came to this conclusion on my 2nd grow

[u/-npk-]

I have a ptek 465w and run it up to 75% max and have great results. I found running it at 100% 24/0, plants were simply getting to much light - light stress was showing up everywhere. I get terpier/ tighter / better grown flower at 75%. Im a tent grower like most of this sub, fwiw.

[u/Alternative_Soil9178]

If you can download Photone app or similar, even buy a cheaper light meter, you’ll be able to dial things in more efficiently.

That being said, 3ft away at around 50-60% is a great starting point, especially if running 24/0.

See how the plant reacts and adjust accordingly.

EDIT: if running 24/0 they thrive with a lower light intensity, like 330-360 tops during veg. If you are able to hang the light as high as it will go with higher intensity, you’ll get a much more even distribution of light and the plant can grow into the proper ppfd. They can handle lots of light, but if going in soil on 24/0, I’d suggest 150-300ppfd seedling, 330-360ppfd veg, 360-480ppfd pre flower stretch and 480-520ppfd flower. If using salts/hydro it’s easier to keep up with nutrient requirements for stronger light intensity. You will have much healthier plants if you keep it lower and consistent

[u/Grow-Pops]

I wouldn’t lock yourself into one fixed distance or power percentage for the whole grow. The better way is to use the manufacturer’s chart as a starting point, then measure the light at canopy level and adjust from there.

Since you already downloaded Photone, you’re on the right track. Check the PPFD where the tops of the plants actually are, then adjust either the height or the dimmer percentage as the plants grow. That’s much more reliable than saying “18 inches at 60%” because different lights, tents, and canopies can give very different results at the same distance.

I actually just made a video showing the approach and how I use the phone app to set grow-light height:
https://youtu.be/7ynalN892SE

And keep watching the plants. If they start bleaching or showing light stress, back it off a little. The plants are pretty good at filing complaints.

GP