High ph runoff

[Rubisco456]

A couple thoughts.

1. Water by it's self is totally shit at holding pH... period. Assuming your RO water's TDS is <25 it's not going to do a good job at maintain pH at all. Even nutrients solutions as high as 1000ppm don't do a good job at maintain pH because they don't have any buffer capacity.
Do your self a favor take some clean RO water take a reading and then add your nutes to it, the pH should shoot up to around pH7.0 or higher. My advice is at small scale: In a gallon of water add your nutrients and mix well, using a pH probe see how much pH down (phosphoric acid, citric acid) you need to get it to pH 6.2 - use that ratio of acid per gallon of nutrient solution and scale as needed. Of course you also need to watch for EC, so there is a balance there of how much acid to add to get your pH where you need it and also you can't add too much that your EC goes out of whack.

2. The Florakleen stuff is just a acidic solution at pH4.0. The idea there is to protonate some of the nutrients allowing them to dissolve and alleviate some of the nutrient lock out that you maybe getting - I've done the same thing using 5mM Citric acid at pH 6.20. I'm not confident of what exact acid(s) it is because the formulation is a "trade secret", otherwise you could add that to your nutes, but with out the additional information I'd say just flush that stuff our after you've used it.

 

[goldenbags]

A couple thoughts.

1. Water by it's self is totally shit at holding pH... period. Assuming your RO water's TDS is <25 it's not going to do a good job at maintain pH at all. Even nutrients solutions as high as 1000ppm don't do a good job at maintain pH because they don't have any buffer capacity.
Do your self a favor take some clean RO water take a reading and then add your nutes to it, the pH should shoot up to around pH7.0 or higher. My advice is at small scale: In a gallon of water add your nutrients and mix well, using a pH probe see how much pH down (phosphoric acid, citric acid) you need to get it to pH 6.2 - use that ratio of acid per gallon of nutrient solution and scale as needed. Of course you also need to watch for EC, so there is a balance there of how much acid to add to get your pH where you need it and also you can't add too much that your EC goes out of whack.

2. The Florakleen stuff is just a acidic solution at pH4.0. The idea there is to protonate some of the nutrients allowing them to dissolve and alleviate some of the nutrient lock out that you maybe getting - I've done the same thing using 5mM Citric acid at pH 6.20. I'm not confident of what exact acid(s) it is because the formulation is a "trade secret", otherwise you could add that to your nutes, but with out the additional information I'd say just flush that stuff our after you've used it.

yesterday i added 5ml voodoo juice and 5 ml b-52 to a gallon split between 3 plants. ph was 6.2 going in 7.2 in runoff and ppm were 139 going in and 331 ppm in run off. Does the ppm runoff have to be lower than what's going in before I can resume feeding?

 

[Rubisco456]

yesterday i added 5ml voodoo juice and 5 ml b-52 to a gallon split between 3 plants. ph was 6.2 going in 7.2 in runoff and ppm were 139 going in and 331 ppm in run off. Does the ppm runoff have to be lower than what's going in before I can resume feeding?

I actually don't think you'll ever get a lower ppm in run off than what's going in - unless you rinse your soil with RO/DI water

Think of the soil as a sponge - It's going to hold on to the nutrients because they are charge particles sticking to the soil particles and when you water in more nutrients you will eventually over saturate the soil as it can only hold on to so much and then the extra will rinse out. This is the reason people talk about a flush with RO or DI water so that you are not adding more nutrients you are simply stripping out what is in the soil. Even if you use RO water you will still get some ppm readings because the soil it's self will dissolved into the water.

pH is kinda the same way soil particles are negatively charged and will hold on to the positive charged ions so when you water all that will come out on the other side of the soil are negatively charged anions that "look" basic to the pH probe.