HELP! Leaves are getting brown spots

[Azalin]

Hello everyone,

First my setup : DWC top fed system on 10gallon tanks. I have the tanks filled with nutrient water (5 gallons) . I am using 600w MH and air pumps with two outlets on each tank. 2 plants per tank. I change the nutrient every 7 days and i check the PH at least twice daily . I try to keep it in the 5.8-6.2 range. Temp in the grow room is 28 C on the "day period" and 23 on the dark. I am using GH flora trio for hard water on 1 third of recommended dosage. ppm is 350. I am using Hydroguard at 2ml per gallon (10ml total)


Now the issue. I topped the plants on the third node (main lining) - (1st out of three planned to get 8 main colas-So now i am at 2). I tried it first on one plant to see if there are any issues. I didn't notice anything for the first 2 days so i proceeded with the rest. On the third day out of a sudden the 1st plant that was main lined reacted as it shows in the pictures. Brown spots and leaves appear burned.







As soon as i noticed the problem i proceeded to a reservoir change. This has seemed to have helped since new growth seems less affected and even newer growth not affected at all. 2 days after the reservoir change i notice that the plant next to itis starting to manifest the same issues.




My only guess is that this is nutrient burn since after the topping the plant had to redistribute the same amount of nutrients to less plant space. But since i am an amateur this is only a guess. Any help at all will be greatly apprecieted folks! I am about to top off again and i am worried i am going to do something wrong. The plants in the other tank are not afftected at all.

One final notice. After every reservoir change the roots appear "painted" as shown in the following pictures. I think it is not rot because i have tried to wipe it with my hand and it goes right off. Furthermore there is not any of the characteristic slime and at the end of the week the colour has been almost wiped clean by the running water. Again only a guess.





Thanks in advance for everything and i hope i have given you enough information.

Azalin

[Redwasp]

I use soil so you need to talk to someone who uses DWC. But I dont think 350ppm is near enough nutrients. Even if it is 0 before you add the nutrients. What is your ppm before you add them? I'm thinking you should be in the 800 to 900 ppm range. But again hopefully a sec grower will chime in.

[Redwasp]

Get someone else's advice before you try this schedule but its what I found.

https://goo.gl/images/CtTWsP

[Toker1]

The roots are stained with nutrients. It’s not an issue. The leaf looks like nute burn, but could be the PH. I let mine get to 5.5 then let is swing up to 6.5 over several days before I adjust it again. More frequent adjustments to keep the range gap smaller are not recommended. I PH adjust 2 times per week.

[Redwasp]

https://www.growweedeasy.com/potassium-deficiency-cannabis

Potassium deficiency. It can be caused by to few nutrients or improper ph.

[Toker1]

This is a chart for ph

[alltatup]

Azalin Nevertheless, the plants look strong! I say nutrient burn; I doubt there's any possibility of nutrient deficiency because you're feeding them cannabis nutrients. However, if you over-feed you may end up with nutrient lock-out, which mean the plants can't intake any nutes cuz there's too much salt.

So lower the nutes!!! I usually start with 25% nutes (different company) and slowly work my way up. And perhaps flush them for 24 hours with plain pH'd water every other week. A flush is a great energizer for cannabis plants.

[Azalin]

Thanks for all the responses!! I started with 1/4 then worked my way to 1/3. In any case i will keep a close eye on them and flush in about 3 days. Then i ll see how it goes from there. Let's hope it all goes well