Worsening heat damage or something else?

[Cwmoore577]

To give an overview of my setup..
Zkittlez auto in Royal Gold Tupur mix (coco) in 2 gal smart pot.
DIY tent that’s 5’ long, 6’ tall and 2’ deep. Temps run 70-75°F and 45-55%RH.
Two lights in the tent, one 100w output blurple full spec led and I put a SunSystem HPS 150 in about half way through this grow.


I’ve had a calcium issue with this plant but nothing maybe, only rust spots on the leaves as well as a bit of heat damage since I put the HPS 150 in there as it does run hot.

It’s gotten way worse in the last two days with the upper leaf edges browning and curling up more as well as the spotting on the upper and middle leaves worsening.

For the majority of the grow I’ve used the General Organics BioThrive line and Emerald Harvest Calmag.
I water between 2 and 3 times a day at 5.9pH, usually and EC of 1.0 or 1000 on my meter and around 700-800ppm.

However the last two days I ran out of the BioThrive line. So I’ve watered with the General Hydroponics FloraSeries line at the feed chart recommendations of 4ml FloraMicro, 8ml FloraBloom, and 2ml Liquid KoolBloom. Also adding the 5ml of the emerald harvest calmag.
Both at 5.95pH, 1100 EC and 800 tds.

My runoff measurements today were 6.03pH, 1.2 EC or 1220 on my meter and 870ppm.


It looks like heat damage to me although I’d like to make sure that the nutrient line switch wouldn’t harm the plant, especially this close to harvest. There was some heat stress but the browning/black edges have gotten significantly worse the last few days.

I’ve tied down the branches as much as possible without breaking them and raised the light as far as it will go.
Lights are about 18-22” above the plants.

The upper leaves look like this..


The lower leaves still mostly look alright..

 

[Rickypsimer]

Yes your gut is Right this is heat stress! What kind of exzaust are you using

 

[Cwmoore577]

Yes your gut is Right this is heat stress! What kind of exzaust are you using

It’s a 4 inch inline fan with a carbon filter.. not the most expensive. Also have a fan in there.

cant think of why it’s gotten worse in the last couple days though

 

[OldMedUser]

Heat stress combined with toxic salts buildup is what that is.

She's burning up from internal salts that have built up in the leaves closest to the lights as that's where she's directing lots of extra water to try to cool herself. All that extra water is bringing extra salts up with it that are frying the leaves.

You should flush out some of the nutes to slow the progress and back the extra light off another 6" at least.

So I’ve watered with the General Hydroponics FloraSeries line at the feed chart recommendations of 4ml FloraMicro, 8ml FloraBloom, and 2ml Liquid KoolBloom.

Way too much at that stage.

 

[Rickypsimer]

The rest of the plant isn't effected? Only the top leaves areas nearest the light right?

 

[Cwmoore577]

The rest of the plant isn't effected? Only the top leaves areas nearest the light right?

There’s spotting that looks like a possible cal def or something else on a few lower leaves but for the most part lower leaves aren’t affected. Definitely not like the uppers.

Heat stress combined with toxic salts buildup is what that is.

She's burning up from internal salts that have built up in the leaves closest to the lights as that's where she's directing lots of extra water to try to cool herself. All that extra water is bringing extra salts up with it that are frying the leaves.

You should flush out some of the nutes to slow the progress and back the extra light off another 6" at least.



Way too much at that stage.

Flush it in coco? So as in a light dose of nutrients?
I give about 40-60% runoff just about every time and the BioThrive line that I’ve used isn’t salt based but I’m not sure if that matters.

I’m unable to raise lights anymore, they’re as high as possible in the tent.

and I’m new to the FloraSeries line and just followed the chart, what ppm range should I aim for if that’s too much?

 

[Rickypsimer]

Always start with about a wet to a half if what the company recommends then raise till you see signs of nite nite but yeah flush your medium with just fresh pH,d wated

 

[Rickypsimer]

Jesus man .. I ment a quarter of the recommended amount on bottle.... Raise until sighns of nute burn

 

[OldMedUser]

I use AN 3-part in soilless and rarely go over 1/2 dose every 2nd feeding and can have toxic salts build from from that. Mainly due to my chronically low RH causing my plants to transpire so much more water and bringing up too many salts with it. I'm going to be feeding at 1/3 and splitting that in half to feed lower amounts in every watering. Thinking that they are getting a big dose and loading up the leaves faster at the feed waterings so with less at every watering they have a more steady ppm without a big spike. Guess I'll know after the next batch is done.

Sorely tempted to set up a drain to waste system but want to get back into DWC and start cranking out some bud for the wife. She's taking bigger doses of RSO all the time. She hasn't touched pot in almost 20 years so I'm surprised she's doing as well as she is on it.

Should get yourself a laser thermometer to check leaf temp. Keep the light so the very top ones aren't more than a couple degrees warmer than the room temp and no more over 80F unless your room temp is over that then it can't be helped.

That toxic salt buildup generally shows up first on lower fan leaves around the middle of flowering but with high temps at the top will show up there first because of the extra water flow to that area. The minerals in tap water contribute to it as well.

 

[Cwmoore577]

I use AN 3-part in soilless and rarely go over 1/2 dose every 2nd feeding and can have toxic salts build from from that. Mainly due to my chronically low RH causing my plants to transpire so much more water and bringing up too many salts with it. I'm going to be feeding at 1/3 and splitting that in half to feed lower amounts in every watering. Thinking that they are getting a big dose and loading up the leaves faster at the feed waterings so with less at every watering they have a more steady ppm without a big spike. Guess I'll know after the next batch is done.

Sorely tempted to set up a drain to waste system but want to get back into DWC and start cranking out some bud for the wife. She's taking bigger doses of RSO all the time. She hasn't touched pot in almost 20 years so I'm surprised she's doing as well as she is on it.

Should get yourself a laser thermometer to check leaf temp. Keep the light so the very top ones aren't more than a couple degrees warmer than the room temp and no more over 80F unless your room temp is over that then it can't be helped.

That toxic salt buildup generally shows up first on lower fan leaves around the middle of flowering but with high temps at the top will show up there first because of the extra water flow to that area. The minerals in tap water contribute to it as well.

Ok thanks for the help.
I’ll got a laser thermometer here somewhere I didn’t think of that.

I watered tonight at the same ratios but dropped the ppm to around 430.. I’ll see if the lower dose helps.