Quote Originally Posted by Help_Needed
That's what I use, not sure on the concentration though.

One thing I've noticed with distilled water is that even though the native pH is 7.0, it is HYPER sensitive to pH Up & Down. Supposedly, 1/4 teaspoon of either will raise/lower a gallon of liquid by 0.5 - so 1/4 teaspoon of pH Down in 1/2 gallon of distilled water should give me a pH of 6.0, right? Nope lol. THREE DROPS of pH Down still drops my distilled water down to 3.2 .

So I've given up on trying to adjust the pH of my water before adding it to the reservoir. I just add distilled water as needed and then check the pH of the res after a couple of hours and *then* I adjust as needed.
when I test my rez, I fill it, then I add my nutes, then I turn on my ph pen and ph correct while my pen is attatched to the side of the rez. I add 1 drop at a time until its at what I want it to be at.

& another question, does ph up & down add to the ppm of nutrient solution?