I used soil one my first grow and only measured the PH going in and not what was coming out into the dishes (used Fox Farm and other nutrients as well) . Towards the end I started to get nutrient burn and lockout and had to flush all my plants. It stunted a few but the rest turned out pretty decent. Would likely have had better harvest if I had checked the outflow PH as well. With soil make sure its about 6-7_recommended for soil mixes. From what I understand different nutrients are best absorbed at different PH ranges within a 5.5-7.0 range. My PH was towards the high end_ 6.5-7.25 once I started measuring the outflow_ so I ended up locking out some of the nutrients. You have to really run a lot of water through a 5 gallon pot for an adequate flush so make sure you do the recommended volume_2x the size of your pots.
This time I went with a completely neutral medium that drains really well but still holds moisture and a lot of air. Using coco, grow stones, rice hulls and worm castings. The plants are now about 7-10 days from harvest and if I run a 1/2 gallon water through a 3 gallon pot it runs through in less than 3-5 minutes once the medium has absorbed ail the wear it can. Downside is you end up watering more often, and with the 3 gallon pots they use up even more water_ lately with the humidity down to 35-45% I'm watering them every day. Another upside is its almost impossible to overwater once they really start growing big time and if you have any problems they are much easier to flush. Never tried the rice hulls before (about 10-15% of my current grow medium)_they seem to be providing more air, better drainage and not so much water retention so seem to be a good additive to the coco which holds more water and has less air space. haven't had any issues with nutrient lockout but I used a suggestion form one of the tutorials and run just water and 1/8th strength nutrients PH 6.0 on every third watering. maybe that has helped?
