Wow, some really out-there advice on this thread.
First up it looks like you're using pH Perfect nutrients. Check the labels of the Sensi - got a drawing of a woman? That's pH Perfect.
DON'T TRY TO pH THAT. It's designed to automatically adjust and hold the right pH, all you're going to do is fight against it and mess it up. Just mix the nutes to the appropriate strength and let them do the rest of the work for you.
Sunshine Mix #4 is what's called a soil-less mix. It's basically the same as running hydroponics, except it works like soil for watering and such. You mix the nutrients in with the water, you water the plants with the nutrient solution, and that's that. All you need to do is just check the run-off to make sure you're not getting salt build-up (ppm higher coming out than what you put in). If you really want to check the pH, knock yourself out, but keep in mind that with the pH Perfect nutes what would be a bad pH for anything else is probably still just fine. They chelated the ever-living crap out of that line so you don't get lockouts like you would with other nutrients if the pH goes a point or so too high/low (probably even farther).
If you're feeding strong and/or seeing some signs of salt-build up, throw in a watering of plain water every so often. In regular soil you'd be alternating one feeding (nutes plus water) and one watering (plain water) because soil has its own nutes in it. With SS#4 a lot of guys run straight feeding.
I would also not advise you to go out and buy more stuff. You have enough. Just check out the Advanced Nutrients feeding chart and try to adapt it to your plants. It's tougher with autoflowers because you don't decide when they go into flower and it can be more difficult to predict when to start Overdrive until you've grown that strain once or twice and know how fast it finishes. Just remember your plants may take longer or shorter (probably shorter) to finish flowering than their chart says and try to adjust for that. When they stop growing taller or just slow down a lot, switch them to the bloom nutes because that's the sign they're kicking into flower mode.
