Lockout?

So my plants leaves have been turning yellow and falling off. It's spreading. I just checked the run off. I ph the water to 6.4, when I checked the run off it was at 6.9PH. So do I put more water in at like 6.0 ph to lower it?

I checked the run off with my ec meter and it was 7.3 mS

Can someone please explain what to do ? I'm new-ish to growing still don't really know how to fix the plant

Tks ahead of time

I answered this question on your other thread, but here's the deal....

I'm not a fan of pH meters unless they are the super-expensive kind. I would advise you to get some General Hydroponics pH test drops.

IF the pH is too high, then yes, you can adjust it by adjusting the pH of the water (going in) to a lower range. Once you get the reading that indicates your runoff is the proper pH range, then you can maintain that range again.

Don't expect instant results. Plants don't work on a human time scale. It may take a couple weeks for the plants to rebound.

This is assuming it IS, in fact a pH issue to begin with.

Growing in what medium?

EC is 7.3?

You got root issues, lockout is secondary to that, fix the roots and your lockout is gone, some of the reasons could be moisture level to high or to low, airflow restricted, temperature too low, or anything that slows metabolism will have a chain reaction effect, Ive just had a similar deal and the problem was the roots were dropping to 14 celsius at night, and I was restricting feeding as I didn't want them to wet at the same time, humidity also was dry as its winter here, it all compounded to lockout and sad plants, I heated the root system to 24 celius, increased the feeds to 4 x 1 minute feeds instead of the one they were getting, within two days they are up happy and powering,