I'm a keep it simple person. I use Fox Farms or Roots Organic. I usually only feed once per entire cycle about 2 weeks into bloom. My plants look pretty bad, lol, but... the end product is pretty solid. I'd say as good as anything you can buy from a CO dispensary. I have a PH pen and I never use it in soil. Coco yes.. Soil no... I use tap water at ph 7.5ish and 60ppm. I don't believe in RO systems and I don't feed my family bottled water. Sure in the hell won't pay for plant water. Lol. IMO, the key to the entire thing is to water to runoff and discard that runoff water (I don't do that either!). Every single thing you've been told by others is true. Don't get all wrapped up in the 20%. Stick to the basics and work out from there. Next thing you know, somebody will chime in and tell you Aluminum foil creates hot spots! This is a passionate group for sure and they take their hobbies (and some cases their health) very seriously.
I can't stress enough... Water when dry, use good soil, add good light, exchange your air, and keep your light timing consistent. That's it. Pot those ladies up in a couple weeks. Don't compare your first grow to what you see on here. I promise you that you will be pleasantly shocked when you harvest and sample your first produce.
Relax... Have some fun!!