I ran 25 gallons. I was running individual 5 gallon buckets but they only had 3 gallons max in them and was always chasing ph. After I built my 25 gal system it was much more stable
You get it dialed in right with a decent size system you don't even gotta do rez changes. I would change once in veg and once after flower stretch and that's it
I never heard of using a wave maker but I definitely wouldn't use it in the same tote as my plants. I ditched the air stones long ago and run spray bars. Roots love it, it's like a real root spa