I love soil grows, wouldn't have it any other way. The greatest challenge I've run into is accurate pH testing. I have an expensive sensor to test run off, but I find it doesn't accurately represent the soil pH a few hours after treatment. I've tried various soil test kits with moderate success. I have three different probes that I use which I compare to try to get a feel for accurate pH. Overall I haven't found any solution to be 100% accurate. Anyone have any suggestions?