Heat Stress + Slow Water Absorption + Discolored / Blotches on Leafs

[Ingvar]

Hi guys,

Got several issues plaguing plants in veg (half-way through the 18/6 cycle). The plants are in large pots, the medium is Sunshine #4 mix, watering with RO water.

The good:

- No drooping of leaves
- Temp (78 F) & humidity (~50%) all within proper range
- Vertical plant growth rate has been as expected
- Middle leaves seem to be fairly healthy (deep green)

The bad:

- Leaves curling on sides (signs of heat stress, which is weird because the lights are at 50% of 1000HPS and 4 feet above the plants)
- Upper leaves are pale green rather than rich green
- Lower leaves are yellow and dying off
- Medium stays wet for a LONG time, like 4-5 days easy (this is a major concern for me, worried about root rot or drowning the plants?)

The pics:



I think the pH might be a little low, and possibly a Calcium & Magnesium deficiency based on some pics I've seen.. but wanted some experienced growers' opinions as well. Thanks in advance!

 

[somebody1701]

CalMag, IMO. Not familiar with sunshine mix though. If you are just using RO water, you'll definitely need to supplement CalMag. Are you feeding anything at all?

 

[RM3]

Have you pulled the root ball from the pot to examine it?

looks like a root problem

note: please always include a whole plant pic, it helps more than most folks realize

 

[xmatox]

Ph looks off, what is it at? As mentioned above you definitely need a little more calmag in your mix if you are using RO water. How bad are you drowning them because it could be destroying the roots. I can't see what size pots they are in, but If you can transplant maybe think about adding in a bit more perlite to the next mix to help with draining if that's still an issue.

 

[Ingvar]

CalMag, IMO. Not familiar with sunshine mix though. If you are just using RO water, you'll definitely need to supplement CalMag. Are you feeding anything at all?

Super light feeding was given at transplanting (about 2 weeks ago) that included full dose of KLN for rooting and ProTekt. Since then it was flushed once (just RO water with about 6.0 pH) until 10% runoff was seen, and then another light feeding yesterday that included a higher pH of 6.7 (water running off tested around 5.7pH, trying to balance it out) was given with the following nutes: CalMag, ProTekt, Foliage Pro.

 

[Ingvar]

Have you pulled the root ball from the pot to examine it?

looks like a root problem

note: please always include a whole plant pic, it helps more than most folks realize

How do I pull root balls from the pot? Any link to a good video reference would be greatly appreciated. Sorry, I'm a newbie to this

 

[Ingvar]

Ph looks off, what is it at? As mentioned above you definitely need a little more calmag in your mix if you are using RO water. How bad are you drowning them because it could be destroying the roots. I can't see what size pots they are in, but If you can transplant maybe think about adding in a bit more perlite to the next mix to help with draining if that's still an issue.

pH is probably around 6.1 or so. It was even lower, I am trying to raise it (see my replies above). I don't think I can do anything to the soil now, since they've been in there for ~2 weeks already.

Do you guys think the leaves curling inwards on edges is not due to heat stress? Can a cal/mag deficiency cause that? Because my plants are 4 feet away from the HPS, and the temps at the tips are a very comfortable 78-79 degrees. I'm baffled and very concerned about this as well as the crazy water retention in the soil. The pots have run off holes on the bottom and I poked even more holes in the sides just in case.

 

[RM3]

How do I pull root balls from the pot? Any link to a good video reference would be greatly appreciated. Sorry, I'm a newbie to this

Very carefully ,,, it's no different than doin a transplant, just bigger and messier

 

[Ingvar]

I am starting to suspect that pH is way too low (acidic). I ran RO that is at 5.7 and the runoff was 5.5. I watered some more with a mix of ProTekt / CalMag / Foliage Pro that was at 6.8 pH. If this doesn't work, I will be officially panicking

BTW - is that the right way to measure soil pH? By recording pH of water coming in, waiting for the run off, measuring the pH of the run off water and taking the average of the two?

Thanks for all the input guys!

 

[somebody1701]

There's something wrong with your PH measuring device if RO was at 5.7.

 

[TacoMac]

I am starting to suspect that pH is way too low (acidic). I ran RO that is at 5.7 and the runoff was 5.5. I watered some more with a mix of ProTekt / CalMag / Foliage Pro that was at 6.8 pH. If this doesn't work, I will be officially panicking

BTW - is that the right way to measure soil pH? By recording pH of water coming in, waiting for the run off, measuring the pH of the run off water and taking the average of the two?

Thanks for all the input guys!

For my own curiosity: I've got a 5 stage RO/DI unit and my water comes out around 6.5 to 7. Are you doing your own filtering or buying bottled water? If you're filtering, have you replaced the filter recently? I'm asking just in case I start seeing this on my end.

 

[Ingvar]

There's something wrong with your PH measuring device if RO was at 5.7.

From everything I've read, it looks like RO water's pH is usually between 5 and 6. Is this not the case for you? I'm using a high-end pH/PPM meter that was calibrated last week.

 

[Ingvar]

For my own curiosity: I've got a 5 stage RO/DI unit and my water comes out around 6.5 to 7. Are you doing your own filtering or buying bottled water? If you're filtering, have you replaced the filter recently? I'm asking just in case I start seeing this on my end.

I'm using a filter and it was recently changed. Does RO actually change the pH of the water coming in? I would be surprised if that were the case.

 

[TacoMac]

From everything I've read, it looks like RO water's pH is usually between 5 and 6. Is this not the case for you?

RO (pure) water is NEVER that low. If it's below 6.5, you have a problem. A big one.

 

[somebody1701]

Mine always came out close to 7. I assumed that was true for everyone but I guess it's different for different systems and input water (as I just Googled this). I assumed since pure water is 7.0, RO water should be close. But since RO water is so pure, the slightest amount of an acid or base will move it's ph in that direction.

 

[TacoMac]

I'm using a filter and it was recently changed. Does RO actually change the pH of the water coming in? I would be surprised if that were the case.

Wait a second. Are you using just a regular filter or a reverse osmosis filter? How about a pic?

 

[Ingvar]

Mine always came out close to 7. I assumed that was true for everyone but I guess it's different for different systems and input water (as I just Googled this). I assumed since pure water is 7.0, RO water should be close. But since RO water is so pure, the slightest amount of an acid or base will move it's ph in that direction.

You are actually right, looks like RO water is around 7 out of the bottle. But upon exposure to air it drops to around 5.6 (info taken from here: https://www.thcfarmer.com/community/threads/what-does-your-ro-water-ph-at.48785/#post-881330). This makes perfect sense for me, because my RO water sits in a reservoir before it gets used. Great point, thanks for bringing it up!

 

[Ingvar]

Wait a second. Are you using just a regular filter or a reverse osmosis filter? How about a pic?

It is definitely an RO filter

 

[BobBitchen]

Pro tekt kicks the PH way up

 

[TacoMac]

I've been using RO water from my 5 stage RO/Di unit for years. Never, ever, even after 5 days of storage has my PH ever been below 6.5.

You have an issue somewhere. I would start with whatever method you're testing your PH with. Get some new test strips or borrow a buddy's tester or whatever it takes, but get a second test method involved in this, because there's simply no way on this earth any RO water is below 6. If that's the case, it's not worth even using.