Need Help with Ongoing Plant Problems

Hi all, I have been dealing with this deficiency (assumed) for several weeks now. It is quite painful to see my plants doing so poorly and I have tried several solutions. I have never posted on a forum for assistance before but this has me stumped, so maybe someone can give some advice. I currently have a sealed room that is supplied with CO2 via a tank. The average temperature is 78 F and the average humidity is 40% RH. The plants are from seed and are just over 5 weeks old. They were fed no nutrients the first week and then were started on a seedling formula. I am using GH Flora series (Gro, Bloom, Micro) and RO water. They are growing in a drip system; they were started in rockwool cubes (1") and are now in pots of hydroton. I started feeding them a mild formula at about 2-3 weeks and soon after that my problems started. The leaves started developing brown necrotic spots in the middle and on the edges. At the same time, some leaves started yellowing and some leaves exhibited both signs. Eventually, they all started showing signs of this deficiency (again, assumed).

I first thought it was a light nutrient burn but then after feeding them water for a few days they did not improve. I then assumed that they were magnesium deficient and gave 1 plant a foliar feeding of epsom salts (1/4 tsp/qt RO water) but it did not improve. Then I bought some Cal-Mag and have been adding that to their feeding regime for about a week and a half. They still did not improve and so I finally arrived at the conclusion that they have a Potassium deficiency due to either high Sodium or due to low humidity/high transpiration rates. I switched to a 1/2 strength Vegetative formula as defined on the GH bottles with the addition of CalMag(2.5ml/gal) and they have been fed that up to today for about a week. This solution runs at about 1.6 EC and the pH has been kept within the 5.6-6.4 range the entire grow(I check daily). Yesterday, I also flushed 1 plant with pH 6.4 RO water and it came out slightly higher, but with a 1.4 EC reading.Today it was flushed again and came out with 200 ppm (.7). So as you can see, I second guess myself constantly and although I had a great deal of confidence in my botanical skills, I am now humbled. If anyone can glean any useful information from the above paragraph and turn it into some advice for me, I would greatly appreciate it. The last pictures are from today. Thanks for any help.
-Peace

You don't mention ph, have you been checking it ?

Sorry, I know I write too much; it's alot of information to sift through lol

trapper keeper said:

This solution runs at about 1.6 EC and the pH has been kept within the 5.6-6.4 range the entire grow(I check daily). Yesterday, ...

Click to expand...

Not sure if I'm right but I tend to keep my ph between 5.8 and 6.0, it may be your ph is too low and too high...just my opinion.

I shoot for those specs as well but I was just saying that the pH has not been outside of that range (5.6-6.4). Those would be the extremes that I get on occasion when I do not pay close enough attention to correcting the pH. Even if those are the extremes, I should not have the type of problems that are showing up, should I?

yes, it is possible. pH is not something to take lightly

OK, so say that it is the pH; if I keep it in the acceptable range (5.6-6.0) for the main elements, how long should I expect it to take for my plants to recover? Also, is there a more expedient way to correct the pH of their systems? (such as flushing with pH correct water?)

flushing with pH corrected water should definitely help, im not a hydro gal so i am not exactly sure. hopefully someone else will chime in soon

Can you check the roots? did you wash the hydroton balls before use?

I cannot check on the roots in the hydroton without potentially disturbing them but the growth that I can see seems good (fine root hairs where the drippers drip). I soaked the rockwool in 5.6 pH corrected RO water and I also soaked most of the hydroton in 5.6 pH corrected water. The hydroton that did not get soaked was old hydroton that I hand cleaned and baked at 200 F for about an hour. These are the steps that I took to ensure that the seedlings got a good start and it worked up until the point when I started adding nutrients.

The nutrients, as I said, are the GH Flora Series and they had been stored in my attic for about a year. I had some old opened bottles and I used them to begin with. Before the problem started or maybe when it was just beginning, I decided to use my unopened nutrients just in case the opened bottles were bad. The unopened nutrients had also been stored in the same attic. I made sure to shake the bottles well before using and I tried to check for precipitates but could not see any. Is there any chance that the nutrients went bad by being stored in my attic? I am in an area where the summer temperatures easily reach 100 during July-August.

Really? No one has any knowledge on the type of problems that I am experiencing? I provided enough information to write a chapter of a book and no one can utilize that information and their knowledge to assist me? I have to say that after all the time that I have spent on this website learning from others posts, I thought that someone would have the know-how to provide at least some rudimentary help.
Thank you to the people who bothered to respond so far but I need something more than a guess at what this problem is. I have already guessed enough so far and I would really like to get my girls back on the healthy route. Again, thank you to those whose tried to help so far but does anyone have any idea what might be going on?

from what i can tell you have a magnesium deficiency. i can tell from the fan leaves that have some rusty parts and then the fan leaves that look completely burnt. Its very common when using RO water. sometimes it starts of with rusty spots on fan leave and sometimes leave tips are burnt and looks like over feeding. leaves then feel dry and then completely turn yellowish brownish. what i would do is foliar feed with epsom salt. and go from there. magnesium moves very slowly in plants so itll take anywhere from 2-3 days to 1 weeks or two. one thing that is good to make a note of is that MJ girls love magnesium.....

i went back and read that youve already foliar fed them with epsom salt at a rate of 1/4 tsp per qt of water. i normally foliar feed them at 2 tbsp per gallon of water. and a lot of the times this wont even help my mag deficiency so then i feed it to the soil. and instead of foliar feeding them with epsom salt since you already did it, try adding some epsom salt to the resorvoir along with the regular dose of the supplemented cal/ma
and even thought you have bben adding cal/mag to your mix chances are that you had the calcium level right but not enough in the magnesium department.

Thanks bestbuds, I will try this this afternoon when I change the nutrients. Should I use the Epsom salts at the same rate that you mentioned for foliar feeding (2 tbsp/gal) or should I use a different ratio?

ive used at at 2 tbs per gallon before and it took care of my problem within 5 to 6 days. once you see that your fan leaves are getting better thats when you stop with the epsom salt. the ;eaves that are really bad wont recover but the ones that have small patches will get better but eventually will die off which is normal

HELP! I added the epsom salts yesterday and some plants look like they may be improving but other plants developed large yellow patches or advanced in the necrosis of some leaves more than they have in recent days. I will post pictures soon but please, if there are any other ideas, share them. I am thinking a potassium deficiency or possibly phosphorus but I doubt it. Are you sure that I should have added 2 tablespoons of epsom salts per gallon of water? It popped my EC levels above 3. This is not good, I am thinking?

My thoughts.....use rainwater....I am going through the exact same thing as you are....just worse! I'm i soil, but having same problems.....My first thought was it was heat problem(so added fan, as I already have exaust fans, and passive intake))....but added a rainwater flush, and waited till next watering. Hit my mother with rain water on second watering after almost killing my plant(still not exactly sure why?), and she stabilized! Am waiting to see what happens? What I see alot on here, is guys trying to fix something with nutes or a plethora of other things, and then they don't know what worked? Or plant dies? What I have learned so far is...."Less is more"....Good luck!
Sorry I couldn't help more!!?
Keep us posted please!