Problem grow leaves clawing drying out

[FLLW]

Through out this grow I’ve had a problem with leaves drying out and clawing.

I don’t think it’s the seeds/plants because I’m growing seeds from three different sources.

I’m in early flower, the lights PPFD is just above 800.

The ppm is in the midrange for the GHC trio plus cal-mag and liquid kool bloom (between 800-900 ppm).

As to the VPD my weekly avg. temp is 72.4 and my average RH 57.6 (around 1.2 VPD). Higher when the lights are on lower with the lights off. The top temp never gets to 80F, usually between 75.0 - 76.6F and daytime humidity averages around 65.0%.View attachment 2562088View attachment 2562089View attachment 2562090

If you look at the photos you’ll see some plants are doing much better than others but all are are affected to some extent.

My water is a mix of RO and well water mixed to around 150 ppm before I add my chemicals. I use Flying Skull Z7 as opposed to hydroguard.

 

[DillyTrying2Learn]

Your pictures do not work

 

[FLLW]

It might be that I haven’t posted enough to be allowed photos.

I’ll try attaching them here:

 

[Smokey_LaFleur]

Looks like nutrient burn to me.

 

[FLLW]

My first guess too. But the numbers don’t support that. I’m using GHC trio @ the midrange and I’m at the low end of their recommended ppm’s.

 

[Smokey_LaFleur]

I don't know much about adding nutrients as I use a "living" soil. Are those nutes synthetic? Perhaps a salt buildup if they are?

 

[FLLW]

I’m not even sure if you can do organic in hydro.
But these are GHC chemicals.

It’s the brand I’ve been using for about seven years and I’ve had tiny burnt tips from nute burn in the past but nothing like this where whole leaves are dying. (Just for the record I checked my ppm’s right before I posted this and all my plants’ ppm’s are in the mid to low range of ppm’s according to the manufacturer).

Not my first hydro-rodeo and I’m scratching my head on this one

 

[Smokey_LaFleur]

Well, never mind my comment on flushing!

 

[JIMKSI64]

Ok is this straight hydro or coco hydro?

 

[ArtfulCodger]

Based on the edge curl, taco-ing, and interveinal yellowing, I'd give them less light. Not sure if that's the main problem, but might be worth considering.

 

[TannedViking]

Looks straight hydro. How's the Ph?

 

[DillyTrying2Learn]

Did you clean the hydroton really good? What's your PH? How do the roots look? 800-900 PPM seems a little high to me but shouldn't be frying them like that.

 

[FLLW]

More info/parameters:
My lights (spider farmers) are set to the low level for flower (slightly over 800 ppfd’s).

Yes this is straight hydro.

I run my pH a little high, generally above 6.0 below 6.5.

I’ve looked at everything or so I thought. I now think my VPD might have been off. Today I was looking at FAQ’s on House of Hydro regarding Ink Bird’s humidistat. The FAQ said make sure your sensor is not in line to catch the direct vapor from your humidifier.

Mine was directly in line with flow. So I moved the sensor. Now my humidifier cycles longer. I’m really guessing here but for the next few days

I’m going monitor how much water my humidifier (house of hydro fogger) uses. I check my humidifier water daily so I know what’s average (usually a gallon a day) in an 8x8 grow room with seven foot ceiling.

If that makes difference I’ll post it.

But I’m thinking VPD.

 

[DillyTrying2Learn]

More info/parameters:
My lights (spider farmers) are set to the low level for flower (slightly over 800 ppfd’s).

Yes this is straight hydro.

I run my pH a little high, generally above 6.0 below 6.5.

I’ve looked at everything or so I thought. I now think my VPD might have been off. Today I was looking at FAQ’s on House of Hydro regarding Ink Bird’s humidistat. The FAQ said make sure your sensor is not in line to catch the direct vapor from your humidifier.

Mine was directly in line with flow. So I moved the sensor. Now my humidifier cycles longer. I’m really guessing here but for the next few days

I’m going monitor how much water my humidifier (house of hydro fogger) uses. I check my humidifier water daily so I know what’s average (usually a gallon a day) in an 8x8 grow room with seven foot ceiling.

If that makes difference I’ll post it.

But I’m thinking VPD.

Im no expert at all but 6.5 seems a little high to me, anything over 6.2 for DWC or RDWC I think is a little to high. Have you checked your light with an actual meter or are you using the photone app? I was having kind of similar problems but not nearly to this extreme and I backed my PH down to 5.8-6.0 and I removed all the cal-mag I was adding and its reduced 95% of the problem. I'd also suggest not flipping to flower like you have when your plants are very stressed like this, much more likely to herm on you.

 

[Smokey0418]

I run a rdwc set up , I get nute burn at 1.2 ec. Or 600 ppm with 500 scale.
Ph 5.8 grow and 6 for flower.
I do not run any co2 and I would ramp up to 800 ppfd but not until my flower is as big as my thumb.
Bumping is great, giving them an idea of what’s to come.
Then once you get the thumbs up , I would put the hammer down.
Then turning down to save the terps at the end.
Good luck with your garden.

 

[FLLW]

This a follow up on my original post:

In my last post I mentioned I was going to move the sensor for my humidistat out of a direct line with the humidifier’s vent.

This is what happened, I went from using one gallon of h2o a day to two gallons. The plants are using less water and new leaves are coming in green and staying green.

I’ve never had this type of problem since I started taking VPD into account. However on this grow I had moved my sensor putting it directly in line with the humidifier’s output. That appears to be the variable I was overlooking.

Thanks to the fellow THC farmers for their advice.