hi mate
i never use chiller, co2 is good idea mate, you will get bigger buds.
you will get good result with your set up.
i use canna aqua vega and flora, canna rhizotonic, cal-mag by Plant Magic and cann PK 13/14.
i use canna start for first 20 days then go on to aqua vega.
i start at EC 0.8, my tap water is EC 0.66 so reall EC is just 0.14 on week 2 i go up to EC 0.9 and up to 1.1 on day 14.
day 20 i go with aqua vaga at 1.1. then i see how plant respond to feed.
I check EC and PH ever day, if EC go up, plant not feeding so i bring EC down by 0.1 if EC go down plant hungry and i up EC by 0.2.
this is how i work out what my plant need.
PH always at 5.8.
i no expert mate but it works for me. i got 8.5 oz from my sweat tooth auto and 10 oz from my TD.
i think i can do better as i still new to autoflower, still learning how to grow autoflower.
hope this helps mate.