Burn or deficiency? Part 2: The Reckoning

Hey. Newb question to follow up. When I pH the water, should I be taking a sample and testing that with the meter or putting it directly in the res?

Because there's a discrepancy between the two. Directly in the res is 5.83. If I test a sample it's 5.96. That's a pretty big difference, so which should I be using?

Just an edit: I've tested and retested, and the discrepancy is always present. Meter is calibrated as of three days ago, so I know it's not wonky. I'm thinking of just averaging the two if no one has a clear cut answer of which is safer to go by.

In hydroponics, either humic or fulvic acids work well, but there are minor differences. If you use RO water, humic acid may be a slightly better choice. Humic acid contains both humic and fulvic acid fractions and it has a buffering effect on pH. RO water alone has practically no buffer for pH. When using RO water, pH can spike upwards during rapid vegetative growth, or crash during heavy fruiting and flowering… sometimes over night! But humic and fulvic acids help buffer pH. In nature, humic and fulvic acids raise the pH of acid soils and lower the pH of alkaline soils. So humic and fulvic acids can help neutralize both acid and alkaline conditions, with a nice moderating effect on your plants. Humic acid also adds more than 62 beneficial trace elements to the water. Since RO water is stripped of nearly all of its minerals, humic and fulvic acids make a great water treatment for hydroponically-grown plants.

Hey guys. Just an update.

There's still some occasional discoloration happening on the leaves of the older plant, and I think it's a pH lockout issue, so adding more calmag probably isn't the solution, but somehow fixing my pH problems. I know I shouldn't be adjusting the pH multiple times a day, but it's either that or it stays below the range of being able to absorb calmag, thus continuing the lockout problem.

Not sure what's causing this perpetual drift downward in pH. I have a res change in a couple of days, and I'll fool around more with it then. Some people are telling me I don't have enough nutes, and I've read elsewhere that having too much in the way of nutes can also be causing this pH drop. So, I have no idea what to believe.

Exudates from sick roots due to improper feeding/low EC is what causes rapid ph drop and you're making things worse by constantly adjusting it.....don't be surprised if root rot sets in as a result (if it hasn't already). Since you're having a calcium deficiency, either get some calmag or raise the EC to 1.5 with your GMB like your hydro store owner said (smart guy).

There are guys here that run their hydro set-ups at 3 EC and upwards (1500+ ppms). I can assure you that you're still in the safe zone from over-fertilizing so don't be afraid to bump her if she needs it. With a proper EC, PH will stabilize and root rot and all that other shit will be a non-issue.

I've been steadily raising it. Currently over 900. Will raise it again this evening as long as I don't see any negative reactions.

But again, it can't absorb calmag if it's always 5.6 or lower. So pH has to be manually raised. I don't see how adding more nutes is going to change pH lockout.

Been trying to help you out dude through all 15 of your threads (not sure why) but you seem hell bent on learning the hard way. I grew hydro for nearly a decade before I switched to soil -- flood and drain, dwc, rdwc, all of it........and I just explained the correlation between the proper EC (not too high, not too low), PH and plant/root health.

Good luck man, you're going to need it.

Would you recommend just doing a res change and raising the EC or should I roll with just raising it with the current res?

Supposed to change it in two days anyway. Not opposed to doing it early.

let's look at some other ideas.
is it possible that this is related to the plant's genetics, meaning could this be a failure of a genetic origin? Is the plant doing this to itself, regardless of pH or ferts?
exactly what and how are you feeding?
what is the water level like? do you have to add water? doing so can change pH and ppm.
what is the temp in the grow space? how warm and cold does it get, or is the temp steady?
to me, the color looks kind of mid to light green. I wonder if low nutes might be an issue and you say that you've been betwenn 600 and 900. do you see any improvement at 900? the brown areas won't come back to green as these areas are dead.
explain more of the grow and grow space. show pics if you can.
I was wondering if your space is warm and that's why you might be getting water evaporation, which could affect pH.

I'm using GH Flora Trio nutes. I always make sure the water level is close to the net pot after early issues I had with part of the roots being too exposed, and that's been resolved.

I have had to add water over the last week. They seem to be drinking a lot. After I add water, I try to get the PPMs back to where they were prior to me adding the water.

Overall, the discoloration looks much worse under LED lighting but isn't nearly as dramatic in normal lighting. Growth has also been pretty explosive as I think it's transitioning into flowering. Both girls showing pistils, no herm that I can see.

And again, the other girl has shown no discoloration whatsoever this entire time.

Here are pics as of five mins ago, along with roots which seem to look fine. Not anywhere near the brown ickiness they were prior to me raising the water level. Not slimy at all.

You can see the discoloration on the older plant pretty easily.

Edit: Forgot about temps. Temps in the tent are usually 68° during the "dark" period and usually around 73-75° during light period.

that actually looks pretty good except for one thing. you see how the leaf edges are curling upward? this usually indicates that the grow space is too warm. 75 isn't bad, it's great outdoors, but indoors this may be a little too warm. it seems silly but it may be a little too much for this plant. people keep using pH lockout to explain almost anything, but is this really the case? if your pH is 5.8-5.9, your pH is fine. I think the range for most hydro is 5.5-6.5. I suspect that heat is playing a role in creating that brown spotting you're seeing because that leaf curling indicates air temp might be too warm. you want a small fan blowing in the area. other than that the leaf color looks good for now. taking another look at your pics, I see that the leaves that have the discoloration are also the ones with the leaf edge curling. it's got to be more than just a coincidence.
In the future, try to put up as much info as possible at first because that saves a lot of time and can get rid of the guesswork.

Update: Been keeping the temps closer to 72-73 degrees, and I also raised the light, just in case this was an issue of light burn(can't do the hand test for LEDs).

EC is currently at 2.28 and pH is still dropping after a res change yesterday. I have never heard, nor read anywhere else but here, of needing to raise EC anywhere near higher than that to stabilize pH, so if the discoloration and pH drop continues, I think I've safely eliminated that as an explanation, rude responses be damned.

And there is no root rot. I can post pictures all day, every day if necessary. The roots are tan/white, with the tan color likely coming from GH Micro which is known to stain roots slightly. They're still drinking a LOT of water.

So, again, insight is appreciated.

it's possible that lowering pH is related to drinking a lot of water. I don't think you raise ec to stabilize pH, I think you raise ec to lower pH. Any brown spotting could be nute deficiency. I don't use GH and not familiar with what it has in it.

polishpollack said:

it's possible that lowering pH is related to drinking a lot of water. I don't think you raise ec to stabilize pH, I think you raise ec to lower pH. Any brown spotting could be nute deficiency. I don't use GH and not familiar with what it has in it.

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Yeah, I'm thinking the spotting is nute deficiency from pH lockout. I'm just going to continue to try to stabilize the pH as best I can. There's no sign of burn, and the PPM IS going down slightly, so she's definitely eating nutes. It's just if it drops too low for too long, it can't absorb calmag.

And the drop is substantial. Over a period of a few hours it's gone from 5.96 to 5.72.

that drop may just be due to water take up, so check that too. and check for algae slime.