About a week ago my girls started to get rust colored brown spots on their leaves that looked a lot like a Mg deficiency. Why there would suddenly by a Mg problem after all this time I couldn't figure out, so I began to think it was a pH problem. Never having a problem like this before, I had to begin manipulating the pH and it is a little trickier than I thought. Every time I set it, it then fluctuates as much a a full point in one direction after turning on the pump. Now I thought that it may be my pH meter because I had been having problems with it in the past but I recently calibrated it and I think its okay. I figure that the fluctuations were coming from juice that was soaked into the root base and the hydroton that is making the pH fluctuate so much after I turn the pump back on but I am still having problems. So now I have the pH stable at around 6.8-7.0 but I'm afraid that the problem is going to continue. I am having the worst time with two OG Kush plants I'm vegging right now. I know that that particular strain is very sensitive but I could really use some comments on my situation just because I have been working it for about four days now, and I'm seeing improvements but not the kind I wanted. I figured if it was a pH problem I would just have to fix it and then everything would be fine, but its not so. My setup consists of four PVC tubes with mesh baskets hanging into them with a few different strains in the whole system. The biggest problem I am having is with the OG Kush and I only have those two girls so I'm getting a little nervous about keeping them alive. Any comments, criticisms, or suggestions would be appreciated. If anything what are your recommended pH values for both the vegging and flowering cycles, and are there any differences for different strains?
Rust colored is usually potassium or calcium. Those spots won't go away even after you flush the plant, and get the ph back to normal.
can you post pics of the rust spots, I agree you need to drop your PH 5.5-5.8 ph is the single most important factor in growing, especially in hydro you say the PH moves a full point when you turn on the pump, are you rinsing your meter off in fresh water after each use? otherwise a coating of the last PH will be on the meter and give you a false reading, till the pump creates circulation and gives you another reading I have one meter that when stirred in the solution, also gives me a different reading, I found that this cheaper meter needs to be left to sit in the solution for a minute to get a TRUE reading
So every time I use the meter, I rinse it off with tap water because the manual for the meter I own, a Hannah instruments pH meter, said not to use deionized water but instead to use tap water so that is what I have been doing. When I said that it moved a whole point, well it did but what happened was this. I set the pH to 6.8, it then went up to 8, I then re set it to 6.8 it then jumped to 7.5 then again to 7.2 and so on. I figured that this was happening because of the water locked up in the roots and the hydoton pebbles that I am using was flowing back into the reservoir and causing a ph change. However I now know that 6.8 is too high and have been setting the pH to 6.3-6.4 and at first there was no problems but then the spots came back after about 24 hours. It was strange though because they began to get better but now the spots are back and when I went to check the pH it read ~5.95. So now I'm thinking it might be my pH meter but even still when I calibrate it, and I place it in solution of acidity of 4.0 it reads 4.0. One thing that I am worried about though is the amount of pH correction solution I am having to put in the water because it seems every time I wake up I need to correct the pH and the ppm is rising quite a bit. And in the end, I am still having a problem, mainly with the OG Kush but all of the plants are showing this problem. One thing it might be is the fact that the plants that are showing the worst right now are the ones with the most established root base. The problem right now is some of my clones are taking longer than I thought so I am keeping the system in a low concentrated solution so the new ones don't get fried but now the older ones are not getting enough nutrients. Do you think this is my main problem and that focusing on pH is incorrect? Again thanks for your time and any comments or suggestions are greatly appreciated. I will send pictures by the end of todays, I just reformatted my computer and I need to renistall a picture editing program to resize the pictures I have from my camera.
here are some pictures. Shown are two different strains, and the really bad leafs are the lower smaller leaves of the OG Kush. Also shown, in the picture with my fingers are new spots showing up on the tips of the Kush leaf.
looks like calcium , potassium & nitrogen locked out try dropping your ph............... 5.5 - 5.8 is optimum for hydro
Okay, so since I have been screwing around with the pH for so long and there is a lot of that up/down solution in the water I am going to switch the chems and run it at a pH of about 5.5 - 5.8. Also I am running 24 hours of light, should I add some dark time in there, or is that okay?
So right now I'm waiting for my RO machine to fill up the the last bucket I'll be using to change my chems, and I will set the new nuts at ~5.7. I will let you know tomorrow to tell you if the problem has stopped. Thanks for your help man, I really appreciate you taking the time to help me with this problem.
Ok, so lets give you an update. I have been running a pH level of ~5.8 and the problem is still there, it is actually worsening. Could this actually be a deficiency because I have been running these guys on a really low ppm of less than 500 for almost two weeks. The reason I am doing this is because new clones have been trickling into the system this whole time and the new ones can't handle the higher nutrient levels that the old one can. But now the old ones are really taking a beating with this leaf problem. This is getting very serious and it needs to be resolved quickly so any more ideas would be really helpful.