J
jacklebee
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- Sep 30, 2023
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Hi, so this is my second grow in a grow room and I keep having soil pH problems. I need some help from professionals, let me start with some backstory
Background as follow:
I completed my last grow with various issues. I was using local peat soil for tomatoes, with a pH level of 6.2 at the beginning.
I gave them one course of generic tomato fertilizer, which I might have slightly overdone with due to reading the package wrong and then immediately got the HESI brand complete package and added that as per instructions on their booklet. measuring the HESI added water gave me a pH reading of 6.4-6.5sh, so very nice, but it seemed that the plants were only getting worse. pH in runoff dropped to as low as 4.9 in on pot and 3.9!!! in the other. Leaves yellowing, calcium, nitrogen deficiencies, etc. Full flower at this point, week 5 or so into flowering.
What did I do? Got a water pH meter, registered the low pH which confirmed my concerns. I also measured my tapwater, which came in at around 7.7pH, so I flushed my pots with the tap water, about 2-3x as much tap water as the pot can hold, whilst removing the runoff water from below.
This didn't do anything to the soil runoff pH (which stayed the same), so I got some pH up from my local grow store. I waited a week for the soil to dry out, whilst the plants were getting slowly more yellow. I added the pH up (biobizz) to the water, raising the water pH to around 8.7, added some Canna calmag once (I thought it would help) and added it to my plants. This actually corrected the pH of the runoff to around +1pH, so 5.9 (mind you I was currently dealing with the first pot), but the plants hated it, probably because the pH of the input water was so high. A week goes by and the first plant starts getting green again, better than before, and I only added regular 7.7 tap water at that point, because lowering that with phosphoric acid seemed like it would further lower the soil pH? The first one was actually fine, after correcting the runoff pH to 6.2sh and having kept feeding it with HESI fertilizers once weekly and the 7.7 tap water otherwise.
The second plant I started correcting later, because it started yellowing later, but I never could correct it, before the end of flower, because the pH had gotten so low.
In my clones room, every new plant, that I start with peat soil would start yellowing pretty quickly. It seems that the pH is kinda getting lower, not higher, as I would guess from the 7.7 tap water? Adding pH up, so the water is 8.0-8.5pH would first really hurt the plant, but then the runoff pH would rise to about 6.0-6.5 range and then watering it with my normal tap water of 7.7 for 1-2 weeks - the plants would actually get better and greener again.
Question that I don't really understand --- Why does my soil pH keep lowering so much when adding any nutes? I am certain, that I am not overdoing it with the nutes. I have phosphoric acid 60% on hand to lower the tap water to 6.4, but it seems illogical to me that when I have low pH problems, I will have to lower the tap water pH, which seems to me that it should in turn be lowering the soil pH as well. But adding any pH up to the tap water, will raise it to an absurd pH, which corrects the soil, but hurts the plants in the short term and then further non-altered tap waterings would make the plant happy, because the soil has an OK pH.
My tap water seems to lower it's pH dramatically very fast, is my gut feel, so it doesn't seem to have much minerals/etc in it, so very low in buffering capacity. Does this seems correct?
So how do you guys do it, when your tap water is above 7 and your soil pH keeps lowering?
My tap water analysis is as below
EC - 420 μS/cm (haha)
pH - 7.4pH on paper
Ammonium - <0.05
Nitrates - <0.010
Iron - 17 μg/l
PS. I just started with my second grow, with the Canna Terra Professional+ soil and after the third round of HESI TNT 50ml/10L (I use 4L, so 20ml per my pretty huge, I guess 30-35L? soil pot) the runoff pH is already at 5.6.
Background as follow:
I completed my last grow with various issues. I was using local peat soil for tomatoes, with a pH level of 6.2 at the beginning.
I gave them one course of generic tomato fertilizer, which I might have slightly overdone with due to reading the package wrong and then immediately got the HESI brand complete package and added that as per instructions on their booklet. measuring the HESI added water gave me a pH reading of 6.4-6.5sh, so very nice, but it seemed that the plants were only getting worse. pH in runoff dropped to as low as 4.9 in on pot and 3.9!!! in the other. Leaves yellowing, calcium, nitrogen deficiencies, etc. Full flower at this point, week 5 or so into flowering.
What did I do? Got a water pH meter, registered the low pH which confirmed my concerns. I also measured my tapwater, which came in at around 7.7pH, so I flushed my pots with the tap water, about 2-3x as much tap water as the pot can hold, whilst removing the runoff water from below.
This didn't do anything to the soil runoff pH (which stayed the same), so I got some pH up from my local grow store. I waited a week for the soil to dry out, whilst the plants were getting slowly more yellow. I added the pH up (biobizz) to the water, raising the water pH to around 8.7, added some Canna calmag once (I thought it would help) and added it to my plants. This actually corrected the pH of the runoff to around +1pH, so 5.9 (mind you I was currently dealing with the first pot), but the plants hated it, probably because the pH of the input water was so high. A week goes by and the first plant starts getting green again, better than before, and I only added regular 7.7 tap water at that point, because lowering that with phosphoric acid seemed like it would further lower the soil pH? The first one was actually fine, after correcting the runoff pH to 6.2sh and having kept feeding it with HESI fertilizers once weekly and the 7.7 tap water otherwise.
The second plant I started correcting later, because it started yellowing later, but I never could correct it, before the end of flower, because the pH had gotten so low.
In my clones room, every new plant, that I start with peat soil would start yellowing pretty quickly. It seems that the pH is kinda getting lower, not higher, as I would guess from the 7.7 tap water? Adding pH up, so the water is 8.0-8.5pH would first really hurt the plant, but then the runoff pH would rise to about 6.0-6.5 range and then watering it with my normal tap water of 7.7 for 1-2 weeks - the plants would actually get better and greener again.
Question that I don't really understand --- Why does my soil pH keep lowering so much when adding any nutes? I am certain, that I am not overdoing it with the nutes. I have phosphoric acid 60% on hand to lower the tap water to 6.4, but it seems illogical to me that when I have low pH problems, I will have to lower the tap water pH, which seems to me that it should in turn be lowering the soil pH as well. But adding any pH up to the tap water, will raise it to an absurd pH, which corrects the soil, but hurts the plants in the short term and then further non-altered tap waterings would make the plant happy, because the soil has an OK pH.
My tap water seems to lower it's pH dramatically very fast, is my gut feel, so it doesn't seem to have much minerals/etc in it, so very low in buffering capacity. Does this seems correct?
So how do you guys do it, when your tap water is above 7 and your soil pH keeps lowering?
My tap water analysis is as below
EC - 420 μS/cm (haha)
pH - 7.4pH on paper
Ammonium - <0.05
Nitrates - <0.010
Iron - 17 μg/l
PS. I just started with my second grow, with the Canna Terra Professional+ soil and after the third round of HESI TNT 50ml/10L (I use 4L, so 20ml per my pretty huge, I guess 30-35L? soil pot) the runoff pH is already at 5.6.
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