Diagnosis help

[Fordprefect42]

Looking for some thoughts on diagnosis/treatment. Basically is my approach reasonable?

These plants are in the fourth week of flower in hydro. GH nutrients plus tps calmag. EC has been sitting around 1.5, but I‘ve been reducing the number because EC has been rising when checked daily implying nute levels overall may be too high. At the moment its sitting at about 1.4

humidity 57%
room temp 75
480 watts of led lighting using hlg qb96 boards
Torus to control ph which had been on the high side at 6.4
peak lux at canopy 65k from a luxmeter

There are 4 plants total being fed by 2 separate reservoirs. 3 of the 4 have the same symptoms.

Some of the pics look like classic and obvious calcium deficiency. The others are harder for me to identify. The edges of the leaves turn turn a reddish color with a couple examples that have progressed to necrosis. I’m really not sure what I‘m looking at there.

Roots look fine.

Given the high nutrient levels in the reservoir I’m doubting it’s a classic lack of nutrients, and I’m thinking this is maybe more of a weird lockout situation.

So my plan is to change the reservoir. Adjust the EC levels to a lower value around 1.3 with a bit of extra calmag. At the same time I’m going to adjust the ph down to about 5.8 with the reservoir reset to get better absorption of calcium. I’m also going to raise the lights slightly to get peak lux down to the 60k range.

Opinions?

 

[HydoDan]

Light stress.. 50k lux is my max..

 

[Fordprefect42]

Light stress.. 50k lux is my max..

Thanks. Too much light did occur to me which is why I raised them a bit. That said I’ve run hotter than this in flower before so I don’t think that level is automatically too much. What part looks like light stress to you? I had suspected the slight bend up along the leaf edges more than the discoloration.

 

[HydoDan]

Thanks. Too much light did occur to me which is why I raised them a bit. That said I’ve run hotter than this in flower before so I don’t think that level is automatically too much. What part looks like light stress to you? I had suspected the slight bend up along the leaf edges more than the discoloration.

The leaves starting to taco and overall appearence.. I've burned a few in my day..

 

[Fordprefect42]

The leaves starting to taco and overall appearence.. I've burned a few in my day..

so same thing I saw. Glad to hear. Agree on the ca deficit? That one seems obvious to me.

 

[HydoDan]

Sometimes light stress can make them appear deficient when they're not.. But a little more cal won't hurt..
Sounds like you're on the right track.. Good luck!

 

[Fordprefect42]

Sometimes light stress can make them appear deficient when they're not.. But a little more cal won't hurt..
Sounds like you're on the right track.. Good luck!

thanks again!

 

[Rurumo]

Just curious, how high are the lights? Are they at 100%?

 

[MustGro]

They don’t look mag deficient to me @Fordprefect42 . Like you said the burn marks look cal def. but I think @HydoDan ’s on the money with light. You’re in week 4 so they’ll take some light now, but you might still want to dim a bit, @Rurumo ’s likely thinking along those lines.
If they’re not taking up ec then that’s not good, especially at this stage of flower. You could make a case for K def in the last pic, but it probably tacoed and burnt the edges. EC of 1.5 isn’t so high, GH runs a high EC in hydro. How’s your water? They must be taking up water though, even if they aren’t taking up EC, or they’d be wilty.
Calcium is more available at ph 6.2 than at 5.8 in hydro; at least from what I’ve read in posts on here.
Me, I’d raise/dim my lights, mix a new tank 1.3 to 1.5 and let the PH fluctuate between 5.8 and 6.2 and see how they looked after that, just like you said.

 

[Fordprefect42]

Just curious, how high are the lights? Are they at 100%?

lights are maxed, but obviously its a combo of light and distance. They could be maxed at 8 feet away and be light starved. Mine were relatively close to get those readings though, probably 20-24 inches, but I didn’t measure.

 

[Fordprefect42]

They don’t look mag deficient to me @Fordprefect42 . Like you said the burn marks look cal def. but I think @HydoDan ’s on the money with light. You’re in week 4 so they’ll take some light now, but you might still want to dim a bit, @Rurumo ’s likely thinking along those lines.
If they’re not taking up ec then that’s not good, especially at this stage of flower. You could make a case for K def in the last pic, but it probably tacoed and burnt the edges. EC of 1.5 isn’t so high, GH runs a high EC in hydro. How’s your water? They must be taking up water though, even if they aren’t taking up EC, or they’d be wilty.
Calcium is more available at ph 6.2 than at 5.8 in hydro; at least from what I’ve read in posts on here.
Me, I’d raise/dim my lights, mix a new tank 1.3 to 1.5 and let the PH fluctuate between 5.8 and 6.2 and see how they looked after that, just like you said.

thanks, pretty much exactly what I’m doing. As far as the ca I had picked up some charts that suggest ca is best under 6. Not sure what’s right, but 6.2 and 5.8 both should be better than 6.5.

As far as water they are drinking just fine losing maybe a gallon a day in each res.

 

[twentyeight.threefive]

Opinions?

The answer is 42.

Looks like too much light. You've already raised the lights so that's good. I definitely wouldn't add extra CalMag. Now that your lights are higher I'd adjust your pH to the proper range for hydro.