Possible light stress, is it too late?

[Bigsledge310]

Bubblegum Auto week 7, was doing 20/4, but started seeing some pistils turn brown kinda early and there have been brown spots on some fan leaves, I was used a PPFD app on my phone and that’s how I was measuring the light which is Spider Farmer SF-1000 even though it was hanging closer than manufacturer’s recommendation. I started wondering how accurate the Photone app is and I decided to raise the light to around 16” above the plant yesterday because of my concern it was getting burned. RUI won’t let me upload the video but there are pics attached. Input is appreciated

 

[lakesidegrower]

I use the Photone app and like it so far - seems accurate enough as far as I can tell. What are your current ppfd measurements? Even around the canopy?

 

[lakesidegrower]

I should also mention that you need to use the right setting for the type of light ur measuring in the Photone app - think I had to ‘buy’ the full spec led setting …. Worth it tho

 

[Bigsledge310]

I did buy the full spec LED feature and before I raised the light I was keeping the ppfd between 700-800 once flowering started, now that I raised the light to manufactures recommendation of 12”-16” it’s closer to 400-600 depending on location since some colas are taller than others and I also rotate the plant a few times a day

 

[lakesidegrower]

Ok - 400-600 is low for flower, but 700-800 right close to the plant could cause stress even though the ppfd isn’t sky high. It’s not really a directly proportional relationship between ppfd and distance and how the plant responds.

Best advice I got was to raise them to like 24” above canopy and then adjust the dimmer from there. Since I did that my lights stay at the top of the room and I adjust the brightness as I go through the run and according to how the plants respond. The SF-1000 is a quality light, is it the one with a dimmer? If so are you getting 400-600 ppfd at max?

 

[Bigsledge310]

Ok - 400-600 is low for flower, but 700-800 right close to the plant could cause stress even though the ppfd isn’t sky high. It’s not really a directly proportional relationship between ppfd and distance and how the plant responds.

Best advice I got was to raise them to like 24” above canopy and then adjust the dimmer from there. Since I did that my lights stay at the top of the room and I adjust the brightness as I go through the run and according to how the plants respond. The SF-1000 is a quality light, is it the one with a dimmer? If so are you getting 400-600 ppfd at max?

The one I have doesn’t have the external dimmer, I believe if taken apart there is a way to adjust brightness but I haven’t messed with it, I do think raising the height is going to be the answer

 

[lakesidegrower]

The one I have doesn’t have the external dimmer, I believe if taken apart there is a way to adjust brightness but I haven’t messed with it, I do think raising the height is going to be the answer

Yea don’t mess with the driver lol I think there would potentially be a way for you to install a dimmer between the plug and the driver, but probably not worth doing. I’m surprised the SF1000 is 400-600 at 16” height… it should be way higher… are you using a diffuser with the Photone app? What’s the exact reading directly below the centre of the light at the canopy level?

 

[LeastExpectedGrower]

Photone is accurate on iPhones but I haven't heard good things about it for Samsung or other phones.

That all said, you should totally play these plants out until they're done. Lots of potential still there.

I did buy the full spec LED feature and before I raised the light I was keeping the ppfd between 700-800 once flowering started, now that I raised the light to manufactures recommendation of 12”-16” it’s closer to 400-600 depending on location since some colas are taller than others and I also rotate the plant a few times a day

Use the DLI setting and also use the calculator on the Photone website... it really helps to dial things in. Make sure you're using the proper weighted paper for the diffuser as well.

 

[lakesidegrower]

Photone is accurate on iPhones but I haven't heard good things about it for Samsung or other phones.

That all said, you should totally play these plants out until they're done. Lots of potential still there.


Use the DLI setting and also use the calculator on the Photone website... it really helps to dial things in. Make sure you're using the proper weighted paper for the diffuser as well.

Great tips - I need to pay some attention to DLI more often…

 

[Bigsledge310]

Photone is accurate on iPhones but I haven't heard good things about it for Samsung or other phones.

That all said, you should totally play these plants out until they're done. Lots of potential still there.


Use the DLI setting and also use the calculator on the Photone website... it really helps to dial things in. Make sure you're using the proper weighted paper for the diffuser as well.

I have and iPhone and I’m using regular printer paper, is there another weight I should use?

 

[lakesidegrower]

I have and iPhone and I’m using regular printer paper, is there another weight I should use?

iPhone here as well, using printer paper. I'd be surprised if that wasn't appropriate - you'd think the app would otherwise specify something different if it was specific

 

[LeastExpectedGrower]

All reports are that the iPhone Photone is very accurate and mine (XS Pro max) matches the par maps provided by HLG for readings. Using the suggested 20# paper.