Appropriate water pH for pro-mix

[KABBAGE]

past results have taught us - hydro (DWC, aero, drip etc...) optimal ph of 5.8
soil/soiless - I personally hover around 6.4 - 6.8 with great results!

Everyone should obviously test ph after all nutrients have been added to the mix. Certain nutrients raise ph and others lower it.
Soiless soil manufacturers (Sunshine/ProMix) try to make the end product as neutral (close to 7) and try to keep it there as much as possible (hence the lime).
If you really want to know what your soil PH is after adding nutes - TEST THE FUCKING RUN-OFF!
The PH tester should be the first thing a new grower should buy, then the according UP or DOWN solution. Not testing your PH can lead to deadly consequences

 

[pineappaloupe]

If your soil is 8.5, your ferts at 6 will bring it down to 7.25 and that's still too high. You need your ferts to be lower, like 5, to balance out your medium to 6.25.

I am not sure the math on that is correct. pH units can't really be averaged like that, 1 pH unit up or down is a 10 fold increase/decrease in H+ concentration.
If you started with a pH of 5, and wanted to get it to 6 by adding a pH 7 solution, you would need around 10 gallons of pH 7 solution to the 1 gal of the pH 5 solution.

 

[skylined]

To be honest I'm pretty sure a lot of the fuckups in my previous grows were due to pH. The color indicating solution is great and all but you really CANT test the runoff, simply b/c the runoff water has a little dirt in it and throws off the color. I would concur that around 6.3 - 6.4 is best for a soiless medium like pro-mix. What I would ask now though is - what is the base pH of the promix, and should one add a little dolomitic lime to keep it more stabilised for the duration of the grow?

Peace,
~Skylined

 

[pineappaloupe]

Promix already has lime added as a pH stabilizer. When peatmoss breaks down it can become very acidic. I am not convinced that we use it long enough for it to break down. Mine was used to veg for 30 days and has been flowering for 43. The total time I will use it will be 100 days or so. Even with using alot of good compost teas to keep the microbes going strong I dont think that is enough time for it to break down enough, or the right environment.
I actually didnt add extra lime to the promix this run (for the floweing repotting) because I was worried with my pH being 7 or higher. And it came back to bite me in the ass in the form of Ca deficiency (shouldve seen that coming after i learned about how much Ca myco eats up).
I hear about soil pH being too high being a bad thing but I have yet to encounter anyone with that problem.
A good pH meter isnt that big of an investment (~$75 for a oakton testr 1) so just pH your water/ferts to somewhere between 6 and 6.5 and its probably OK.

this is only my first run using mostly promix (I add 1 part EWC and 1 part FFOF or so), so I too am still learning. next run I am going to try a few things. one bieng to add the recommended ammount of lime to the mix because Ca is eaten by myco, and the other being to not add dolomite and use sensical regularly.