yellowing upper leaf tips

[az2000]

Changing lights also changes demands of the plant. Most LED growers seem to need more Mg I never really looked into why but I probably should.

I thought about that, but it doesn't look like mg. And, presuming the CXB is providing more/better light than the mars & galaxy, the plant would eat more (which should reduce the chance of accidental overfeeding)?

To me it looks like nute burn, or a deficiency like you and others say.

But, I still think it's significant that the OP has grown for 6 years and has a gut feeling it's the lights. His own lux targets are too high compared to modern household LED lightbulbs. That makes me think he developed those with a less efficient light, and is now giving too much more-efficient light.

Watts per square foot might clear that up. CXB cobs are probably in the 25w/sq ft range. If he's using it in that range, then it probably isn't the lights.

 

[Aqua Man]

I thought about that, but it doesn't look like mg. And, presuming the CXB is providing more/better light than the mars & galaxy, the plant would eat more (which should reduce the chance of accidental overfeeding)?

To me it looks like nute burn, or a deficiency like you and others say.

But, I still think it's significant that the OP has grown for 6 years and has a gut feeling it's the lights. His own lux targets are too high compared to modern household LED lightbulbs. That makes me think he developed those with a less efficient light, and is now giving to much more-efficient light.

Watts per square foot might clear that up. CXB cobs are probably in the 25w/sq ft range. If he's using it in that range, then it probably isn't the lights.

Yeah... I looked for that too. I. My experience light burn will cover more leaf area. But I don't feel confident enough to say it's not either lol. Definitely more ppfd out of that fixture but if his lumen is the same as previous it shouldn't be different. Only the height would be.

 

[Greenmile]

Yeah... I looked for that too. I. My experience light burn will cover more leaf area. But I don't feel confident enough to say it's not either lol. Definitely more ppfd out of that fixture but if his lumen is the same as previous it shouldn't be different. Only the height would be.

here some photos of previous project in same growbox and conditions , its mid flowering stage and you can see a little progress of yellowing leaves

 

[Greenmile]

guys , i just checked runoff and it seems my plants dont feed at all, i used tap water which was 150 ppm, ran through pot and it shows 950-990 ppm :(
but ph is normal , somewhere between 6 -7 ,

when i water with nutrients the solution is about 950 ppm and 6.2 - 6.5 ph, when just watering its 150 ppm and 7.2-7.3 ph.

if ppm is wrong should ph be ok ? ? ?

 

[az2000]

tap water which was 150 ppm, ran through pot and it shows 950-990 ppm :(
but ph is normal , somewhere between 6 -7 ,

That runoff ppm doesn't sound bad to me. That's about where mine would be at that stage. In flower I'll be in the 1600-1800 range. I get lockout around 2400-2500. (But, this stuff seems to vary by soil. I've seen people with rich soil post very high ppms and not have lockout. However, I think low ppms suggests there isn't a problem with overfeeding.).

when i water with nutrients the solution is about 950 ppm and 6.2 - 6.5 ph, when just watering its 150 ppm and 7.2-7.3 ph.

Testing runoff is dubious, and I think it's more dubious for ph. How long the solution remains in the soil, and how much solution displaces that (and dilutes it) can affect the results. There is an "official" way to do it. Google for "NCSU Pour-through extraction method." If someone just pours water through until they get runoff, that may not be very accurate. I think ph is less accurate from that. You have to let it set in the soil for a period, and then displace just enough to measure.

However, if you're feeding 950ppm that sounds high. But, if you've grown for 6 years, I'm sure that's worked for you in the past.

 

[oldskol4evr]

guys , i just checked runoff and it seems my plants dont feed at all, i used tap water which was 150 ppm, ran through pot and it shows 950-990 ppm :(
but ph is normal , somewhere between 6 -7 ,

when i water with nutrients the solution is about 950 ppm and 6.2 - 6.5 ph, when just watering its 150 ppm and 7.2-7.3 ph.

if ppm is wrong should ph be ok ? ? ?

6or 7? got to dial in on precise number friend,plant dont flux like that,there picky,how much did you use to flush it,flush with your tap,the ppm is cool what ph is your water another thing,you gonna have to run more water threw to flush the stuff out,when you get close then check ph and get it dialed in ,then take your nutes and ph adjust were they supose to be,950 aint it,never mind i dont think your getting a rednecks picture,sorry to bother

 

[Aqua Man]

here some photos of previous project in same growbox and conditions , its mid flowering stage and you can see a little progress of yellowing leaves

What nutrients are you using? I'm going to guess bloom nutrients. Do you notice this more when you switch to bloom nutes?

 

[Mr.Juice]

I found an interesting site, going back to the lux/PPFD discussions you were having. Put your lux and pick the type of light and it will do a conversion,

Convert Lux to PPFD - Online Calculator | Waveform Lighting

Online calculator to convert illuminance (lux) to PPFD (micromoles per second per meter squared).

www.waveformlighting.com

 

[az2000]

Definitely more ppfd out of that fixture but if his lumen is the same as previous it shouldn't be different. Only the height would be.

I didn't understand that. You can have many more ppfd than lumens. HPS would produce less ppfd per lumen. CXB cobs would produce more ppfd per lumen.

 

[Greenmile]

6or 7? got to dial in on precise number friend,plant dont flux like that,there picky,how much did you use to flush it,flush with your tap,the ppm is cool what ph is your water another thing,you gonna have to run more water threw to flush the stuff out,when you get close then check ph and get it dialed in ,then take your nutes and ph adjust were they supose to be,950 aint it,never mind i dont think your getting a rednecks picture,sorry to bother

i have only ppm meter, i dont have ph meter at this moment, i checked with ph paper strips, i ran 1.5-2 liters of water through pot and waited for about 2 minutes,.

 

[Greenmile]

What nutrients are you using? I'm going to guess bloom nutrients. Do you notice this more when you switch to bloom nutes?

this problem starts from early weg and slowly progresses in late flowering stage

 

[az2000]

this problem starts from early weg and slowly progresses in late flowering stage

You're using Fox Farms "trio." Isn't that for soil? And, you're in soilless?

Again, if this is a new problem I don't think it's your nutrients. But, I would use hydro nutrients (like GH Flora 3-part) in peat, without any soil added to it. Using nutrients that depend on an organically-active soil seems like it could be problematic.

 

[Aqua Man]

I didn't understand that. You can have many more ppfd than lumens. HPS would produce less ppfd per lumen. CXB cobs would produce more ppfd per lumen.

Was thinking LED to LED should not be to much different and looks like same issues previously if I'm reading the post right... Sometimes I'm challenges like that. But again it could be light burn but I'm leaning away from that. I could be wrong it's not like that's anything new lol.

 

[Greenmile]

You're using Fox Farms "trio." Isn't that for soil? And, you're in soilless?

Again, if this is a new problem I don't think it's your nutrients. But, I would use hydro nutrients (like GH Flora 3-part) in peat, without any soil added to it. Using nutrients that depend on an organically-active soil seems like it could be problematic.

what do you mean ? if i use peat and perlite its not soil ?

 

[Beachwalker]

when i water with nutrients the solution is about 950 ppm and 6.2 - 6.5 ph, when just watering its 150 ppm and 7.2-7.3 ph.

Too much nutrient
Too much pH fluctuation

 

[az2000]

what do you mean ? if i use peat and perlite its not soil ?

Technically that's soilless (like coco and peat, or perlite by itself). The ph is supposed to be a little lower (than soil). It's basically an organically inert environment.

I'm not saying soil nutrients won't work. But, it seems like the wrong stuff to use together. I.e. if you want to use soil nutrients, I would soil that soilless with 20% soil. (Improve the conditions for soil nutrients to be broken down by microbes.). The advantage of soilless is you feed the roots directly, like hydro. If you use soiless medium for that reason, I would use hydro nutrients.

That's typically how that's supposed to go. But, that's not to say people haven't successfully used hydro nutrients in soil, and soil nutrients in soilless. It just doesn't seem like the best match to me. It wouldn't surprise me if there were probems.

But, if you've been doing this and not had problems (which I thought your first post suggested, and that you had tied it to lighting change), the "trio" probably isn't the problem.

 

[Aqua Man]

I'm a hydro grower so I can't tell you what you should be feeding was wondering if it was organic because sometimes availability can be an issue. To me it's looks like sulfur or micros. Still leaning to lockout. But that's just my opinion. Possibly ph or nutrient buildup. Peat is very acidic so the runoff ph and a slurry test would help but I think you need a better ph testing method. 6.5 is about where you want it. That's about all the info I'm good for. If you flushed then give it a few days to a week and see if it's getting worse. Damage leaves will likely get worse and die but it should not spread. In the meantime try to measure the runoff ph and ppm. Also maybe do a slurry test to see where your soil is sitting. Without that info I'm stuck and will just be grabbing at straws

 

[az2000]

6.5 is about where you want it.

That's for soil. (And, soil ph can swing a full point between wet and dry. I don't believe it can be locked in as precisely as hydro.). Soilless should be between 5.5 and 6.0.<<link

When I grew soilless, I think I did 5.8-6.0 in veg, and 6.0-6.2 in flower. (I can't remember).

 

[Aqua Man]

That's for soil. (And, soil ph can swing a full point between wet and dry. I don't believe it can be locked in as precisely as hydro.). Soilless should be between 5.5 and 6.0.<<link

When I grew soilless, I think I did 5.8-6.0 in veg, and 6.0-6.2 in flower. (I can't remember).

Never used peat other than to buffer pH naturally in aquariums. Assumed it's more of a soil. Either way I can't see it being a good medium but that's just my uneducated opinion. To acidic.

 

[MIMedGrower]

That's for soil. (And, soil ph can swing a full point between wet and dry. I don't believe it can be locked in as precisely as hydro.). Soilless should be between 5.5 and 6.0.<<link

When I grew soilless, I think I did 5.8-6.0 in veg, and 6.0-6.2 in flower. (I can't remember).

Pro mix for example is buffered to 6.3. But i guess coco needs lower.