Quote Originally Posted by carinia
Also if the ingoing ph is 6, and the outgoing is 5.0, your soil ph is 5.5, which is too low, not to high.
This is incorrect. If the outgoing is 5.0, the medium would have to be BELOW 5 to lower the water to 5. If the medium were 5.5 and the water is 6.0, how did the water get lower than the medium on the way out????

I would suggest investing in a PH pen. They have a digital readout and also do temperature (most). They require regular calibration, but it's worth the effort. Also try to find one with 2 point calibration rather than one point, they are a little more accurate.

As far as how many drops of PH down to change your solution, that is going to depend on if you are feeding, or if it's straight h2o. I usually add just under 1ml to my nute solution, and it brings it down around half a point. It's going to be hard to be accurate without a digital reading. Some guys can tell with ph strips, or the test solution, not me. Just one less thing for me to screw up with the pen:thumbsup: And I'm all about eliminating operator error when possible:stoned: