I can't figure this out (full op details)

System info:
Ebb and Flow hydroponic system
Hydroton supporting rockwool cubes
Water every 1.5 hours for 15m

Environment:
5x5x8
24/0
Temp 74-79f
RH 47%-52%
Proper ventilation, circulation
c02 is around 600ppm and is not supplemented
Kind LED k5 series XL1000 (1)
Lights currently too close to canopy at 24" (working on it)

Reservoir:
Temp ~75f
RO water ~5ppm
Light rarely penetrates
Circulation pump
pH is kept at a constant 5.8 with controller
Technaflora nutrients ~70% strength, up from 30% at the beginning of grow as the ppms continually drop.
Changed every ~7 days. Haven't been flushing.

Plants:
3 Great White Shark and 2 Girl Scout Cookies (same res)
1 month, 3 weeks old from seed

Recent ppm readings (RO water):
4/7 - New Reservoir, no flush, 770ppm
4/8 - 704ppm
4/11(was away)- 540ppm
4/11 Topped off to 782ppm
4/12 - 612ppm
4/13 - 532ppm
4/13 - Topped off to 830ppm
4/14 - 734ppm
4/15 - 671ppm

Hey guys, this is my first grow in several years. Thanks so much in advance for taking the time to read this and help me out. Any ideas are greatly appreciated.

As you can see from the images, the plants are suffering some kind of nutrient issue. Or maybe it's light burn? I really don't know, that's why I'm here. I originally thought this was a Cal-Mag deficiency, but the lower leaves seem mostly unaffected. It's only the newer vegetation that is afflicted. There are a small amount of lower, month+ old leaves that have browned and died, however, most of it looks okay.

Interestingly enough, the smaller Girl Scout Cookies are seemingly untouched by this issue. Beyond some recent leaf tip twisting they look really good. Perhaps this is a strain specific issue with the Great White Shark? This is another factor that makes me think it's a deficiency. The smaller, less nutrient demanding plants are fine (mostly fine!).

I have been adding about 10% more MagiCal to my mixes. That did not seem to help, so I foliar sprayed with an RO/Epsom salt mix against my better judgment (because the lights are 24/0). I feel like they looked worse the next day. After some research, I don't think it's a Ca or Mg problem anymore (lower leaves mostly unaffected, stems bend easily). Though, how long would an epsom salt treatment take to work anyway?

Also, I included images of the root systems of a Great White and a Girl Scout. The Great White roots look slightly brown and have a black substance attached to them. What on earth is that? Thrive Alive B-1? Have I struck oil? The Girl Scout roots look much cleaner. The images are both from the same chute in my system.

Maybe I just need to flush more? I'm at a loss guys. I've been trying to figure this out for weeks. Any suggestions for my grow or reading material or anything would be appreciated.

Thanks,

Kinetic

Perhaps I should simply sing to them more?

Forgot to add - they are vegging.

Have you considered giving them a little break from the light?

MrBungle said:

Have you considered giving them a little break from the light?

Click to expand...

I've since raised the light to around 30". They shouldn't need a break in my experience.

But, I have discovered something interesting just today when I peeked into my res. It's filling back up after a feeding but nothing is coming out of the drain tubes. It appears as though the solution is flowing back through the pump. I imagine the roots are clogging up the drainage system.

Perhaps the problem is that too much nutrient is remaining in the chutes due to the clogging? I'd really hate to cut on the roots to solve this issue?

So this is kind of cool and confusing. The shorter black piece is the drain and the taller one is attached to the pump. Like I said, nothing comes out the drain, but the res fills back up after a feeding. Trying to understand how the chutes were empty if nothing is "draining," my first guess was floating water. Then I remembered that my ppms aren't THAT low.

In my flood and drain. My tall one is the drain. And the short one is the one that fills my table. Seems might have your hose on the wrong one. As for the plants looking like maybe something with nutes or fluctuations in ppm. I used to use hydroton and had problems. I know you got to rinse the hydroton in ph water before use i have read. Sorry cant be more help i ended up getting rid of the hydroton and switched to coco

Just_Grow said:

In my flood and drain. My tall one is the drain. And the short one is the one that fills my table. Seems might have your hose on the wrong one. As for the plants looking like maybe something with nutes or fluctuations in ppm. I used to use hydroton and had problems. I know you got to rinse the hydroton in ph water before use i have read. Sorry cant be more help i ended up getting rid of the hydroton and switched to coco

Click to expand...

Hey, thanks for the response!

I was wrong, the tall one is actually the drain in mine as well. And I put this thing together LOL.

As far as ppms, I haven't been able to find the equilibrium yet. I have been gradually adding a larger percentage of nutrients throughout the grow. My readings have for the most part always been on a downward slope. In the early phases when the plants were around 1' there was a point where they were consuming more water than nutes. But they've continually outgrown my expectations, so yes the ppms are not steady. I was not expecting an issue because, like I said, I have been upping the number every reservoir change and topping off between. It would surprise me if I was so far from the equilibrium that it would cause this much damage. But it's possible. Thank you for bringing it to my attention. I'm going to do a 100% strength solution tomorrow.

What were your problems with hydroton? I soaked mine in a solution of tap water (150ppm) and hydrogen peroxide beforehand.

That was my problem exactly. Couldnt get ppm or ph to stablize. No matter what i did it would move up amd down even a little and i noticed slower growth and smaller bud sites. When i switched to coco got it figured out. I can set my ph amd ppm. And leave it for week or two amd just watch my monitor. I usually let the ph swing a little not much before i bring it back down i have noticed the plants like that alot.

I have read where some growers have had ph issues because of hydroton that was not rinsed properly. I can't imagine it would have any impact on ppms unless it was added to the system fresh from the bag and the dust traveled to the res?

I think my plants are just in consumption mode because I just added 1070ppm (100% strength) of solution and it was down 110ppm after the first feeding. Not to mention, in the last 15-24 hours they consumed 4-5 gallons of solution.

They grow like 2 inches a day and have outgrown the space already. My main goal for this grow is to get as many clones as possible (because I'm new to cloning and need practice) but damn, there's no room to flower now.