Dude, I had a post about a week ago about me tuning my 300w led from 75% to100% and instantly got light burn at 30" from canopy...turned it down to 50% and cropped/ LST'd them...a couple days later, still new growth distorted and yellowish new leaves with even lighter yellow edges and tips...so I turned the light to 25% and they are loving it!?!? I'm about to start them on flowering in a few days...how should I approach turning the light up to 100% for flower? I know they will only be getting 12 hrs of light but am just scared of having repeats of light burn and slowing growth down. Any suggestions? This LED is blowing my mind lmao
300W Marshydro LED is no joke
- Thread starter Cheschire
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Deketx
Well-Known Member
Got a tsl2000 and light bleached the hell out of my plants this grow . Get a lux meter off Amazon and use it to set your heights or power.
They have a par footprint on their site that should give you an approximation as to what the par is at a certain distance from the plant.
Delps8
Well-Known Member
If you can get the conversion chart, similar to this one from HLG, to use with the lux meter, run with it. Without a conversion chart, your readings will be off because a lux meter measures different frequencies of light than plants use. I've attached a diagram from HLG that shows what the light meter reads compared to PAR.
Lacking a conversion chart, snag a copy of Photone. It's not as accurate as a $600 meter but it'll get you pretty close.
There are lots of sources for guidelines re. what your PPFD should be and the meter will tell you how many photons you're getting from the light but the plants will tell you how much light they can handle. PPFD at the canopy is a function of the dimmer control and the height above canopy. If you go leave your light at the recommended height (I use 18"), you can fine tune the light level. Set the PPFD to the low end of the range and ramp up, say, 50 or 100 PPFD per day. If you start seeing the symptoms you were getting before, back off to the previous setting.
When PPFD goes up, you start hitting the law of diminishing returns. Once you get over 700 or 800 PPFD you're not going to continue to increase photosynthesis as rapidly unless you up the temperature and add CO2. Seeing that you're using LED's, you should boost your ambient temp enough that your leaf temp is high enough. Check out this chart.
- Thread starter
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Yes, this chart helps. I downloaded a ppfd app, downloaded the par chart footprint from Mars hydro and calibrated it as close as I could and seems to be accurate enough I'm not bleaching tips yet...lol. I did not have an actual conversion chart that looked accurate to what the specs were for the light. Thank you friend! This a screenshot of the app screens...not actual readings! Lol
Delps8
Well-Known Member
Yes, this chart helps. I downloaded a ppfd app, downloaded the par chart footprint from Mars hydro and calibrated it as close as I could and seems to be accurate enough I'm not bleaching tips yet...lol. I did not have an actual conversion chart that looked accurate to what the specs were for the light. Thank you friend! This a screenshot of the app screens...not actual readings! Lol
You're on the right track, amigo.
Happy growing!
