"Runoff pH is useless" or "Keep an open mind"?

drbudkilo

Member
The statement that "runoff pH is useless" is going around RIU. It seems to be a statement which clearly states 100% lack of usefulness.

I have an open mind about runoff pH. While I don't use Hydrobuddy, I do use a spreadsheet and make my nutes from scratch. It's a PITA, tedious and time consuming, and requires concentration to avoid mistakes. I've been able to successfully alter runoff pH by altering the nute's nitrate:ammonium ratio. I didn't discover this, instead read about it. I thought it common knowledge that ammonium sulfate (AMS) was acidifying, but maybe that knowledge was due to my lawn-care background. Manipulating the ratio of nitrate:ammonium in my nute formulas seems to change runoff pH in predictable ways. Therefore, the statement "runoff pH is useless" is false. You can certainly argue its usefulness, but useless means it lacks any usefulness.

For those who buy their nutes in easy-to-use nutrient bottles and who are not trying to change the manufacturer's designed nitrate:ammonium ratio, maybe tracking runoff pH is useless. I don't know. Here's one RIU post which may explain the rationale behind the statement "runoff pH is useless":


The poster said that a soil slurry test is preferable to runoff pH. Maybe it is, for measuring potting mix pH. Is that the same thing as runoff pH? Taking a small core of potting mix which has a plant actively growing in it will likely damage some roots.

The scientists who wrote the following report used runoff pH as a data point:


It is my belief that since I can alter runoff pH by altering the nitrate:ammonium ratio, I should set runoff to a pH value which cannabis plants are known to like and where good mineral absorptions occur. Will it make any difference in the overall performance of my grows? I don't know.

For those who believe "runoff pH is useless," would you mind pointing to any peer-reviewed journal reports which make that assertion?
well I test runoff fir EC. usually you run a 15% overflow to keep the EC within 50% of feed EC..usually for carbon based media feed is 1200 Us ( 1.2 EC ) with runoff up to 1800 Us ( 1.8 EC) . ph is usually not an issue in carbon based media . rockwool I run 1700 Us feed 2400 Us runoff .
 

drbudkilo

Member
The statement that "runoff pH is useless" is going around RIU. It seems to be a statement which clearly states 100% lack of usefulness.

I have an open mind about runoff pH. While I don't use Hydrobuddy, I do use a spreadsheet and make my nutes from scratch. It's a PITA, tedious and time consuming, and requires concentration to avoid mistakes. I've been able to successfully alter runoff pH by altering the nute's nitrate:ammonium ratio. I didn't discover this, instead read about it. I thought it common knowledge that ammonium sulfate (AMS) was acidifying, but maybe that knowledge was due to my lawn-care background. Manipulating the ratio of nitrate:ammonium in my nute formulas seems to change runoff pH in predictable ways. Therefore, the statement "runoff pH is useless" is false. You can certainly argue its usefulness, but useless means it lacks any usefulness.

For those who buy their nutes in easy-to-use nutrient bottles and who are not trying to change the manufacturer's designed nitrate:ammonium ratio, maybe tracking runoff pH is useless. I don't know. Here's one RIU post which may explain the rationale behind the statement "runoff pH is useless":


The poster said that a soil slurry test is preferable to runoff pH. Maybe it is, for measuring potting mix pH. Is that the same thing as runoff pH? Taking a small core of potting mix which has a plant actively growing in it will likely damage some roots.

The scientists who wrote the following report used runoff pH as a data point:


It is my belief that since I can alter runoff pH by altering the nitrate:ammonium ratio, I should set runoff to a pH value which cannabis plants are known to like and where good mineral absorptions occur. Will it make any difference in the overall performance of my grows? I don't know.

For those who believe "runoff pH is useless," would you mind pointing to any peer-reviewed journal reports which make that assertion?
I also make my own feed solutions from base compounds
 

simpleleaf

Well-Known Member
No I mean EC - Electrical conductivity.

thats what I use to measure nutrient strength.
The SI unit of conductivity is S/m and, unless otherwise qualified, it refers to 25 °C. More generally encountered is the traditional unit of μS/cm.
The EC meter I had, which I bought at ebay (maybe a year ago) and which recently broke, measured EC in microS/cm (µS/cm), and by using a mode switch, it also measured PPM. Most of the folks on this board use an EC figure based on milliS/cm (mS/cm), which according to Wikipedia is not the traditional measure. As an example only, 1 mS/cm = 1000 µS/cm, both are basically equivalent EC measurements. I'm not sure why folks on this board use mS/cm, when the inexpensive tools available measure in µS/cm, it's possible that more expensive tools measure in mS/cm, I'm not certain. When using the related scale PPMs, as the tool I had measured it, 500 PPM = 1000 µS/cm. Fucking confusing, yes?

To confuse matters even further, there are two other common PPM to EC conversions. The following table appears to use mS/cm scale for their EC numbers.


So, here was the basis for my prior question, and I believe I took the calcium and magnesium hydroponic PPM values from Smart Fertilizer:

elementPPM, lowPPM, high
calcium​
80​
140​
magnesium​
30​
70​
Totals110
210

Therefore, I'm wondering how you only add 0.2 EC to get those PPMs? The only thing that makes sense to me is you're using the EC scale mS/cm, because 110 PPM = 220 µS/cm = 0.2 mS/cm, but you'll note that's the low end of the range.

Damn, that was a lot of typing and thought, and it is certainly possible I've made a mistake somewhere.
 
Last edited:

jondamon

Well-Known Member


The EC meter I had, which I bought at ebay (maybe a year ago) and which recently broke, measured EC in microS/cm (µS/cm), and by using a mode switch, it also measured PPM. Most of the folks on this board use an EC figure based on milliS/cm (mS/cm), which according to Wikipedia is not the traditional measure. As an example only, 1 mS/cm = 1000 µS/cm, both are basically equivalent EC measurements. I'm not sure why folks on this board use mS/cm, when the inexpensive tools available measure in µS/cm, it's possible that more expensive tools measure in mS/cm, I'm not certain. When using the related scale PPMs, as the tool I had measured it, 500 PPM = 1000 µS/cm. Fucking confusing, yes?

To confuse matters even further, there are two other common PPM to EC conversions. The following table appears to use mS/cm scale for their EC numbers.


So, here was the basis for my prior question, and I believe I took the calcium and magnesium hydroponic PPM values from Smart Fertilizer:

elementPPM, lowPPM, high
calcium​
80​
140​
magnesium​
30​
70​
Totals110
210
Therefore, I'm wondering how you only add 0.2 EC to get those PPMs? The only thing that makes sense to me is you're using the EC scale mS/cm, because 110 PPM = 220 µS/cm = 0.2 mS/cm, but you'll note that's the low end of the range.


Damn, that was a lot of typing and thought, and it is certainly possible I've made a mistake somewhere.
I take it on the basis of the basics as follows.

1.0EC is the same as 10CF or 500ppm at .5 or 700ppm at .7.

i use EC because 1.0EC is 1.0EC.

i don’t deal with ppms as there’s too many conversions and calibrations for ppm depending on which calibration ppm you use.

EC is the universal standard.
 

jondamon

Well-Known Member


The EC meter I had, which I bought at ebay (maybe a year ago) and which recently broke, measured EC in microS/cm (µS/cm), and by using a mode switch, it also measured PPM. Most of the folks on this board use an EC figure based on milliS/cm (mS/cm), which according to Wikipedia is not the traditional measure. As an example only, 1 mS/cm = 1000 µS/cm, both are basically equivalent EC measurements. I'm not sure why folks on this board use mS/cm, when the inexpensive tools available measure in µS/cm, it's possible that more expensive tools measure in mS/cm, I'm not certain. When using the related scale PPMs, as the tool I had measured it, 500 PPM = 1000 µS/cm. Fucking confusing, yes?

To confuse matters even further, there are two other common PPM to EC conversions. The following table appears to use mS/cm scale for their EC numbers.


So, here was the basis for my prior question, and I believe I took the calcium and magnesium hydroponic PPM values from Smart Fertilizer:

elementPPM, lowPPM, high
calcium​
80​
140​
magnesium​
30​
70​
Totals110
210
Therefore, I'm wondering how you only add 0.2 EC to get those PPMs? The only thing that makes sense to me is you're using the EC scale mS/cm, because 110 PPM = 220 µS/cm = 0.2 mS/cm, but you'll note that's the low end of the range.


Damn, that was a lot of typing and thought, and it is certainly possible I've made a mistake somewhere.
My bluelab truncheon measures in EC CF PPM but I only use EC.

my water is 0.2EC on my truncheon.

add Calmag to make the truncheon read 0.4EC then I add my base nutes.

you really making things more difficult than they need to be lol.
 
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