Call me dumb, I'm sure I'm missing something, BUT: I have one of those PH test sticks that displays the PH and can be calibrated by a small screwdriver, bringing the levels up or down depending on the direction the screw is turned. I have PH test liquid, 7.0 and 4.0, and have calibrated my stick to those levels. QUESTION: I have a RO water filter, the water that comes out is 7.1 PH nearly all the time, sometimes fluctuates a few points but nothing huge. After calibrating my PH sticks the first time, and then testing the water and finding out the true PH of my RO water from the tap... Couldn't I just use the RO water in the future now as a "Test solution" since I now know it will always be within a few points of 7.1? Whats wrong with this thinking, other than being absolutely sure the PH its exactly 7.1 each time. Would it really matter if it was .2 off? I have plenty of test solution, this was purely hypothetical. Thanks!
RO isn't quite as pure as the de-ionized water used to make up calibration solutions. The simple fact that yours fluctuates any should tell you it's not a stable standard. While it may not be critical for what we're doing here, I'd prefer to know I'm on the money.
.2 to much in either direction could result in a nute lockout which you NEED to AVOID or else your plants wont get the food she needs resulting in a number of different problems which in return could cause a lose of yield if not corrected. I hope crankz advice and mine help but these are just our opinions ðŸ˜