Yes you use all three of those and they probably recommend buying 4-6 other things to play mad scientist with too.. LOL
AN like to make their customers feel like they are doing important thing throughout the grow.. adding this or that at various times, but this contradicts the neesd of theplant in lieau of marketing nonsense to sell more bottles, :P they also needlessly split nutrients up, again, so you buy more bottles.
e.g. there's no reason not to include the micros in other of the other two bottles.. the fact it is separated is retarded. Ca and Si are the only things you need to keep separate. Ca will form a precipitate with sulfur or phosphourous at very high concentraions, but not at the concentrations we fertilize at.. so the bottles of concentrate need to be separate in these cases.
use a phone app or online calculator. Since you are providing 100% of plant needs, keeping track of ppm of each element is very useful for a faster trial and error learning curve to hone a formula that works well for vege and bloom. you may need a bit less N in bloom -10-20% less... or if you overfeed it in vege, you may need even less than that.
Fertilization is about weeks and months adding up and not what you did last night. take notes, even einstein can't remember daily details for the past 1 or 2 months of fertilizations and adjustmnets etc etc... plus, when you see a leaf symptom, you have somethign to look back on.. it may not be helfpful as ayou gain experience, but once you form some baselines from comparison, it is much easier to diagnose issues and eliminate other potential possibilities. leaf symptomes are not 100% discrete.
1.3-1.5 EC feed every time with a religious 10% or more runoff... can't go wrong. Soilless/hydro is really the same thing no matter what substrate or brand you chose. There really is no difference in quality of these ubiquitous ingredients used for fertilizer.. ammonium nitrate is ALWAYS ammonioum nitrate.. there's no higher quality ammonion nitrate. A guaranteed analysis label is very accurate.. more accurate than a TDS ppm measurementn by far - mathematical certainty.
So, you can mix brands without fear... fertilizers are fertilizers...
there are some differenet options to provide 1 nutrient or another, so there is some variety and potentially better products than others, but the ingredients themselevs are still ubiquitous commodities. If something has Ca or Si, mix it in AFTER you have fully dissolved or mixed in other parts of fertilizer products.
Again, at normal feeding concentrations you will not get a precipitate. the concern is in the stock solutions mixing together, which you obviousyl don't combine bottles, lol... and that intial point of mixing it in... add anything with Ca and Si last.. no problems will occur.
plant needs are pretty consistent... cellular reproduction doesn't all of a sudden need drastically different things. It is anecdotal myth that you need to have a super sophisticated constantly changing formula. this contradicts our generational knowledge....knoweldge gained from employing the scientific method and not someone's ego-driven conclusions from their basements with no control group and a tiny sample size.