My poor relationship with ppfd

[Rama777]

Yo! I was watching a video with Bruce Bugbee, discussing DLI at various stages of growth. He recommends as much as 1,000 ppfd for veg. Odd because if everyone started doing that, we'd all be burning the shit out of our plants. So okay, strike against that supposed knowledge.

More average I see people talk about 300-600ppfd being solid targets during veg. My issue is that I never can seem to get past 200ppfd in veg without having issues. That's been consistently true for damn near every strain and veg stage of growth I've gone through. There must be some missing variable that I can't seem to figure out that would explain why I can't seem to push light as much as most decent growers.

Temperature is the most obvious variable I can think of. Undoubtedly our plants wouldn't be able to take as much light in 60 degree temps versus 80 degrees. Same I'm sure is true for 70 degrees versus 80. But like right now I'm at 80 degrees in my tent and sill can't push past 200ppfd. Anybody got any bright ideas? Pun intended..

 

[Smokey_LaFleur]

I have to ask the wattage of your light and how close to your plants do you run them?

 

[Rama777]

I have a 250 watt bar style light in a 2x4 that I drive at 40-50% with a distance to canopy of 36”. That seems to keep things happy. I’m not sure if it’s 40 or 50% with the wonky way the dimmer knob was designed.

This is for my veg stage.

 

[Smokey_LaFleur]

That's a head scratcher. Can't figure how a 250 watt light set at 50% 30+ inches away would be burning your plants! I'm guessing you have a meter or app to measure your ppfd?

 

[BearWater]

These are 352 watts. I havent ppfd’d these at all but the plants started and in solos are loving the height and full output. The taller plants in the one gallons were getting too close to it and not liking that so I turned it down to 4 lights. Not precise at all so sorry for that but im not all convinced at the “scientific absolutes” on some of the topics out there

 

[Ninjadogma]

What do your light manufacturer's data sheets and charts say, and does your light metering track with what the manufacturer says it should be at specified distances from the plants?

Above my knowledge level but I believe a setup with supplemental CO2 allows for higher PPFD. That seems to be the caveat to placing plants in a super high PPFD without cooking them.

 

[Blastfact]

Unless you have a meter you don't know what you don't know. In this pic I was at 800 PPFD and thought I was having nutrient issues, environment got to hot,,,, yada yada yada. Turns out it was PH. I use a want to be organic one arm super soil. It will deal with PH up to the high 7 range and down to high 5 range right out of the tap. And as I found out if the tap PH is in the 8's stuff don't work right at all.... LMAO

 

[Rama777]

Unless you have a meter you don't know what you don't know. In this pic I was at 800 PPFD and thought I was having nutrient issues, environment got to hot,,,, yada yada yada. Turns out it was PH. I use a want to be organic one arm super soil. It will deal with PH up to the high 7 range and down to high 5 range right out of the tap. And as I found out if the tap PH is in the 8's stuff don't work right at all.... LMAO

View attachment 2346970

I did discover recently that the water I switched to was raising the ph because of high alkalinity. It is possible that’s been part of my issue. However when my ph was likely in better check, I would still get the issues. Now to be more clear, the majority of my light stress issues appear as magnesium stripping. One thing that tends to happen is that they respond better when they get repotted. The magnesium stripping slows down or stops for a while.

I guess now that sort of starts to maybe point towards the answer? Could be ph problems regardless of which water I’m messing with, or COULD be lack of magnesium but I doubt it because it’s always actively stripping mag from the upper canopy. My understanding is that a true magnesium deficiency will affect lower leaves as well.

 

[Rama777]

And here’s a reference photo for the typical issue.

 

[Rama777]

I mix RO with well water now until I get to a total alkalinity of around 90 (no longer considered hard water, but approaching near it) which ends up with a TDS reading of 75ppm and a ph of 7. Unless I’m missing some key information, that should be a pretty good base water. After my nutes I adjust the final ph of the solution to about 6.2-6.5

 

[Smokey_LaFleur]

Sorry, maybe I missed it... what medium are you growing in? I usually don't worry about ph. I'm growing in a coco based living soil. I do test the ph of my water occasionally, but I'm adding nothing but some cal mag every watering so ph is generally not an issue for me.

 

[Rama777]

Peat based and synthetic nutes.

 

[Blastfact]

I don't worry about so called hard water unless it loaded up with sulphur or salt which some folks have in there well water. Which I do not have to deal with at all. People that do have hard water around here with lots of calcium and iron grow great plants. Whats the PH after your nutrients are all mixed in the water? I'm doing a organic soil. But not a living soil. And it can deal with tap water PH as long as it's no higher than 7.8 or and no lower than 5.8-.9. If the tap gets out of that range I have to adjust the PH. Got lazy and just figured that out... I should be able to get my PPFD back up in the 800 range by the weekend now that I've pulled my head out of my ass...

 

[Rama777]

I don't worry about so called hard water unless it loaded up with sulphur or salt which some folks have in there well water. Which I do not have to deal with at all. People that do have hard water around here with lots of calcium and iron grow great plants. Whats the PH after your nutrients are all mixed in the water? I'm doing a organic soil. But not a living soil. And it can deal with tap water PH as long as it's no higher than 7.8 or and no lower than 5.8-.9. If the tap gets out of that range I have to adjust the PH. Got lazy and just figured that out... I should be able to get my PPFD back up in the 800 range by the weekend now that I've pulled my head out of my ass...

Depends on how much I’m feeding but typically around 6.5-6.8 after adding my nutes.

As for hard water, that typically refers to dissolved solids like calcium and magnesium. Alkalinity on the other hand is a result of bicarbonates. Those can be calcium bicarbonates, not to be confused with calcium carbonate which is what’s in most cal-mag products. It’s not the hardness that will screw you up as much as the total alkalinity value.

My well water is close to a 9 ph straight out of the faucet.

 

[Rama777]

What do your light manufacturer's data sheets and charts say, and does your light metering track with what the manufacturer says it should be at specified distances from the plants?

Above my knowledge level but I believe a setup with supplemental CO2 allows for higher PPFD. That seems to be the caveat to placing plants in a super high PPFD without cooking them.

The manual for my migro light says to be 20” and somewhere between 60-100% for veg, whereas I’m usually stuck around 36” and 40% power. Quite the conundrum..

 

[Captspaulding]

What do your light manufacturer's data sheets and charts say, and does your light metering track with what the manufacturer says it should be at specified distances from the plants?

Above my knowledge level but I believe a setup with supplemental CO2 allows for higher PPFD. That seems to be the caveat to placing plants in a super high PPFD without cooking them.

Well, I’ll tell you this brother you know 100%. I’m in the camp of take that shit out of the box immediately and fucking burn it those PPFD charts and all that stuff is like the bane to new growers existences man I spent like two years fucking dispelling that bullshit after all these new growers fried their shit under that fucking madness But seriously dude oh my God it’s a pet peeve like the output settings that they recommend for their lights basically across the board it’s really really broad. You know because it’s not about what a light can do it. It’s about what a plant can do under the light if that makes sense.

 

[Captspaulding]

The manual for my migro light says to be 20” and somewhere between 60-100% for veg, whereas I’m usually stuck around 36” and 40% power. Quite the conundrum..

You know me,
Rabble rousing.

Your using what we like to call “ a happy medium”

Alright my work here is done
Love ya buddy!

Ima whistle past the ol graveyard now.
Beat me up later

 

[TheGoldenRoad]

See I feel like a walking clusterf*** now because I never gave rise to ppfd before this grow. Plant tips get white? Turn the light down. That has always been the plan. But this grow I got the Photone app to keep track of what I was putting the light at and when. Throughout most of veg I was around 350-475-ish. I’m in week two of flower and it was around 680-ish on Friday. I have two 150 watt panes and the 680 is at 80% power. I don’t know if that helps but I’m off my soapbox.

 

[Captspaulding]

See I feel like a walking clusterf*** now because I never gave rise to ppfd before this grow. Plant tips get white? Turn the light down. That has always been the plan. But this grow I got the Photone app to keep track of what I was putting the light at and when. Throughout most of veg I was around 350-475-ish. I’m in week two of flower and it was around 680-ish on Friday. I have two 150 watt panes and the 680 is at 80% power. I don’t know if that helps but I’m off my soapbox.

I was just talking with Rama about it the other day like basically the way I do it is I set my light way higher than it needs to be at and output lower than it needs to be, then it’s a slow incrementall Uptick all through veg endeavoring to try and get it as close to the broad flowering low range guidelines that float around out there that way I can always just drop my light if I need to if the plant starts to stretch too much and the nodes get too much space in between them i’ll drop the light and lower the percentage for a couple of days just by like three or four points and then after this couple few days, I’ll start raising it back up again on the output side when I used to adjust all these things that was my game but nowadays, I don’t touch shit except for my modulation for light output. If need be but a lot of the time I’m already clicking it up. I’m watching my plants harden off to it as I’m working it.

 

[Florida_Mike]

right now i'm running 720w @ 100% 24" from top of the plant. they get constant feed

with highly oxygenated nutrient solution. in soil you can't supply that much.

i'm running @ 86f & 800ppm/co2. @1400ppm co2 i can push it up to 95f no prob, they eat that

shit up. the key is that the constant feed allows them to pump water and nutes to

the top of the plant muck faster, which causes faster transpiration, which keeps the leaves

cool, the same as us sweating. it's dependent on all parameters being at or near

100% efficiency though.

in the past i burned 4 - 1000w hps' over a 4x9' area (2 side by side connected to 2

more, side by side w/ 8" sealed cooling hoods. clones when on the slabs w/ just 1 light on,

next day 2, then 3, then 4 (i had friends who were burning 6k over same the area).

each of these "pods" would average 10lbs every 87 days. the lights were mounted

fast to the ceiling, which was covered in 3/8" plywood, so you could stick screws &

hooks etc. anywhere you needed them; without worry.


-peace-