Ph Up Or Down

[foxman711]

I know that the PH scale is logarithmic, i.e. a solution with a PH of 5 has ten times the number of H- ions as a solution with a PH of 6. Does this mean that if it takes 100 ml of PH down to lower the PH of a given volume of solution from 7 to 6, it will only take 10 ml to lower it from 6 to 5?

[ToadInCan]

As a general rule, the answer to your qusetion seems to be yes. However, I wouldn't rely on that formula without testing the results. As the concentration of hydrogen ions (H+) increases, a solution becomes more acidic. As the concentration of ions that bond with H+, such as hydroxide ions (OH-), increases, a solution becomes more alkaline. The water here in Michigan changes seasonally, and the particulate salts which bond with H+ vary. Also, any nutrient solution, or change in nutrient solution, will effect the concentration of ions that bond with hydrogen. I believe that it's just a task which must be done throughout the growing process, and adapted to the current conditions.