Back in the early 70s Kmart was selling bright yellow, green or orange coveralls made out of nylon - cheap. lots of old farts were wearing them. I was working at a gas station when an old man was pumping his own gas and he splashed fuel all down the front of a pair of these, then proceeded to brush down like to brush the gas off. A static spark ignited him and that nylon melted instantly to him. I grabbed a fire extinguisher and put him out but he was dead before he hit the ground. So I have no problem telling people what not to do at the gas pumps. I don't ever need to see that again. In our pyro training we were taught that cell phones and radios can ignite vapors or fireworks in a box. I am skeptical about this one but never used my phone around the boxed product and I am uncomfortable watching people pump gas and talk on their phones.
Ok let me expand on this, if you have buffered your coco properly, you always fertigate to 20% run-off and your fertigation is always between 5.6 PH and 6.1 PH Then you do not need to monitor the coco for PH. The only thing that will be changing the PH in that pot is the roots themselves. Roots exude substances that signal the microbes to make various nutrients available to the plant. This can and does change the PH in the root biome, it is desirable. leave it alone. In DWC when the plant transitions into flower it can drop the PH from 5.8 to 5.0 in just a couple of hours, I actually had it go to 4.8 once. This is the signal to do a P-K boost. I also would only correct PH to 5.5 for a couple of days at this time before going back to 5.8.