You need ph and ppm calibration solution for your meters. If you got cheap ones you need to calibrate them before every use. If you got good ones, do it once a week just to be safe.
Dont over feed and make sure that your ppms are slowly falling. If your ppms are slowly rising you need to dump half of that out and use RO water to dilute.
Dont add to much to your pot. . . All you really need is nutrients. As a beginner I wouldnt be adding bloom boosters, silica, enzymes and whatever else people tell you to add. . . Keep it simple then do what you feel is right once your past the learning curve. There is a reason to add things, we can always add different things, but theres a time and place for it.
Nutrient line all of us are familiar with is Flora trio and
calmag. That is really all your plants need to produce high quality weed. Now the bloom boosters will help bring out the terps and bulk up your buds, if you have issues, all it does is amplify them and make them harder to diagnose. Get 1 good grow under your belt then go wild.
3 plants in a 2x4 in hydro is a bit much. I would keep them down to a 2 week veg if you run 3 PHOTOS.
I wouldnt run autos, I would run photos so you get a good concept flowering and vegging. Make them do what you want for now, and keep it simple. . .
I use to run heaters for my live system while most people run chillers in their sterile system. You will find more help available that doesnt conflict when you run sterile. . . most people do it that way. If you go live, expect conflicting information from those who run sterile. Live in my eyes is easier in the long run, but does amplify the learning curve.
You can run your system like a lake using natural bacteria, or like a home swimming pool that uses corrosives to kill all microorganisms, like peroxide, h202, bleach and other additives. You cannot add h202 to a live system, and you cannot add natural bacteria to a sterile system. Its one or the other. . .
Keep leaf temps at 77f, res temps under 72f, humidity under 50%. Download the LUX meter and give your plants around 5k to 10k lux for the first week.
Test your system without plants in it. Turn your lights up on max, let it run idle. . .check your temps, upgrade your exhaust fan if it gets too hott.
Dont give up, I have yet to grow a bad plant and have never grown in soil or dirt.