True about accuracy of testing runoff. However, imho, it can be a useful indication of conditions in the root zone. In my ph issue, I actually reached out to fox farms and they emailed me instructions for a 1:1 and a 5:1 soil slurry test with acceptable ph ranges to expect. Outside these ranges conditioning would be required to bring medium back in line. In my case, I tested some remaining mix from the bag and the results also showed unacceptabably low ph. During the subsequent flushing to raise ph and lower nutrient accumulation, I learned another hard lesson and that was that nitrogen is one of the easiest elements to release in a flush situation. Hence I then had N deficiency so then had to up the N as well. It seems every lesson I've learned has been the hard way and the majority self inflicted. Yeah, fox farms should have better QC of their potting mix but it taught me to slurry test every mix before using. Sorry to be so windy and hope you find the root of unhappiness in your (slightly) droopy one.I haven’t checked PH at all during this grow, As I’ve been avoiding runoff, but I will check next watering. Also water only so far.
In regards to measuring soil PH;
When I first started out I was using liquid salt based nutes, naturally I have experienced the whole “omg my runoff is out of range, let me flush it into correction w water that will offset the PH imbalance.”
during that point in my growing career, I reached out to a real GOAT on this forums @Renfro. And he was explaining how checking soil ph through runoff is inadequate. And the only real way to do it is using a soil probe, which I’m not trying to spend a couple hundred on right now.