Low pH corrected - How long till change occurs?

Hey guys,

Story is, everything was going well and was getting what looked like 'nute burn' from hot soil that was 50/50 FFOF/LW, the seedlings (from seed) outgrew this issue but then other problems developed. My question for now though:

My pH meter was in need of a calibration, water that I had been using was reading 6.5 (distilled) so I did not pH balance it, I just watered my plants which are in 1.5 L pots @ 4 weeks old, each plant received 2 cups of water once the soil had dried at least 2 inches down into the soil usually every 4-5 days. Well yellowness started occurring, blotchy dark-green spots on leaves, and then the new growth all started canoeing very rapidly. On a whim I decided to test my meter in calibration 7.0 fluid, it was reading 7.8, then I tested the distilled water I was using AFTER i calibrated my meter down to 7.0, the distilled water read 5.5! So basically I have been using 5.5 pH water on my plants, I quickly mixed up a 2 cup/per plant does of water for the plants, pH adjusted it to 6.5 and gave them a watering. This was confirmed by the fact the water runoff was 5.8-6.0, in my last watering the pH runoff was 6.5, this is due to the incorrectly calibrated pH meter. Therefore what I think happened was I was giving the plants 5.5 pH water that read 6.5 (incorrectly, my fault), and the pH runoff read 6.5, both were in fact 5.5.

How long until my corrections in pH will show up in new growth? I read that weeks 3-4-5 are crucial for environment influence on sex (stress) for MJ. How royally could I have screwed the pooch on this by slipping on something as simple as calibrating my pH meter.

I will add pictures later today after X-Mas festivities, just wanted to get this post up to get it exposure to people who had 5.5-ish pH for a period of time then corrected it to see their responses to the situation. What I suspect is Mag def due to nute lockup, and possible excess salts from the buildup of nutrients that bound together. Just as a side every time I water I sustain 10% runoff. The light is a 1000w MH @ 24 inches, canopy temp 73 day, nighttime 73 (digital programmable space heater), humidity 40%, 18/6 light cycle.

They have been given only water except they were given a nitrogen boost with AN Dr. Hornsby Iguana Juice Grow @ 2.5 ml mixed in 2 gallons of water (25% nute schedule suggestion, PPM = 50 from 0 of distilled) at the middle of week 3, very diluted solution. All symptoms were present BEFORE the watering with nitrogen. At week 5 I was going to up the pots to 3 gallons or 1.5 gallons, I have both coming in the mail (square pots), so that could be a solution for any excess salts built up in the soil, new soil in 4 days? The plants are exactly 4 weeks + 3 days old.

Picture #1 Spots developing

Picture #2 Spots seemingly spread until they form a blotchy center mass, the leaves start turning pale yellow at this point

Picture #3 This shows the 'canoeing' of the leaves, they buckle up a bit, making the leaves resemble a canoe.

Merry Christmas.

If the pH is off by quite a bit, then a flushing with water of the proper pH is helpful. Just run the water through and test the runoff. If the runoff isn't where you want it, then run some more water through until the runoff pH is where you want it. That's what I've done in the past and it seemed to work for me. Wait for others to reply, because they might have a better answer for you, but I think my method is good.

Bump.

Alistair Young said:

Just run the water through and test the runoff. If the runoff isn't where you want it, then run some more water through until the runoff pH is where you want it.

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Even at the risk of overwatering? I gave them a watering last night, if I watered them again would that be stressful, but less stressful then them sitting @ 5.9-6.0 pH (tested runoff), which I believe is what my last watering (at 6.4 pH) brought the 5.5 pH level up to, as per my thought that they were watered with 5.5 pH?

Tact said:

Bump.



Even at the risk of overwatering? I gave them a watering last night, if I watered them again would that be stressful, but less stressful then them sitting @ 5.9-6.0 pH (tested runoff), which I believe is what my last watering (at 6.4 pH) brought the 5.5 pH level up to, as per my thought that they were watered with 5.5 pH?

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Get the pH right, then let it dry out.

The overwatering will be WAY less stressful than the pH being off.

Think about it, what about plants outside that endure 2 or 3 days of straight rain? They are soggy for a few days, the rain stops, they dry out and life goes on.:hubba:

CONTINUED over watering is a bad thing. Once in a while like to fix the pH will do little harm.

DD

The only other thing I can think of is Cal-Mag deficiency due to using distilled water with 0 ppm, that is unless FFOF/LW has cal-mag in it to suffice?

Waiting on a few other people to chime in here with a time estimate on when things will re-balance with the now adjusted 6.5 pH water?

Tact said:

The only other thing I can think of is Cal-Mag deficiency due to using distilled water with 0 ppm, that is unless FFOF/LW has cal-mag in it to suffice?

Waiting on a few other people to chime in here with a time estimate on when things will re-balance with the now adjusted 6.5 pH water?

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You will see it in the new growth, good or ill.

The leaves that suffered and are marked will stay that way.

Don't know if that mix has the cal-mag to suffice or not. I know my mix doesn't, but dolomite lime takes care of it.

DD

FFOF contains crushed clam(?) shells for cal and mag, sufficient for several weeks. BUT... I still like to add a tsp or three of lime Once your ph is back within acceptable levels, the plants will respond within days..IMO/E. The damage won't repair itself, but the new growth will show it.
"Over watering" is a symptom caused by keeping the medium 'too' wet for extended periods. It is virtually impossible to over water with a single watering. I agree "flush" w/ proper ph and allow them to dry out, then resume feeding as normal.

Hick said:

FFOF contains crushed clam(?) shells for cal and mag, sufficient for several weeks. BUT... I still like to add a tsp or three of lime Once your ph is back within acceptable levels, the plants will respond within days..IMO/E. The damage won't repair itself, but the new growth will show it.
"Over watering" is a symptom caused by keeping the medium 'too' wet for extended periods. It is virtually impossible to over water with a single watering. I agree "flush" w/ proper ph and allow them to dry out, then resume feeding as normal.

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Thanks for the replies Alistair, Droppy Dog, and Hick.

I flushed the plants today, in total the 6.33 cup plants (1.5 L pots) have received 7 cups of water with a pH of 7.0 roughly, the runoff-water was measured at 6.4-6.5 pH. So I think I rebalanced the pH with the flush, they are very waterlogged so I am going to let them sit for the better part of a week until the pots feel light again, then water them and transfer them to either the 1.5 gallon or 3 gallon pots coming by mail.

Something new though, the new leaf growth on some of the plants are exhibiting what looks like nute-burn? Could this be from the nitrogen boost I gave them a week ago? It was only 2.5 ml mixed into 1.6 gallons of water (about 25% of what they suggest on the label), each plant received 2 cups of water, which at the time was most likely OFF in pH around 5.5 instead fo 6.5 (due to incorrectly calibrating pH meter). One thing to note, I did this TWICE in one week, at this diluted dose, if it would have been one feeding it would of been 50% of one recomended dose, I did two @ 25%, the idea was to influence females with N at crucial week 3-4? Either way the solution that if it was to much N would be to flush em correct, so can't do much other then wait?

I will attach pics, these are the same plant at different angles, under the HID (sorry about that), but I circled the burnt tips which are visible better at different angles depending on the leaf tip.

Hey bud,

Really solid input from all the above. I totally agree with our friend Hick... Overwatering is watering too often, before the medium dries out. Overwatering is not giving them all that they need when you do water and even flushing the medium won't cause overwatering if you always let your soil dry out between waterings. I think the slight burn is maybe from giving them the 2nd dose of Iguana Grow in a row rather than one *light bump*. The first app was probably sufficient and the combo of the organics still present in the FFOF and the repeated app of nutes looks like it's just a bit more than they like to get. Just give your plants water for a while and in a couple of weeks you should be able to give your plants some light nutes keeping in mind that they seem to be nute sensitive. Like mentioned above it's water under the bridge now and there is no way to 'fix' the damaged leaves but the good news is we don't smoke the leaves and by the time your plants finish up these few damaged lower leaves will be a distant memory as you look at your dank budz...

Peace!

Thanks DOS, I will update you in Yahoo, and on here in case others use this post as a reference for low pH and flushing themselves.