I have used all sorts of reactors over the years , ( from cheaper models up to $700 + Deltecs ) and had found no matter what style or model I used I was always finding I had to tweak the flowrate at least weekly if not more. Seemed like there was always something to be fiddling with. I now have been running my Dosing system on my tank for almost 6 months ( Profilux ) and I must say I can not believe I didn't switch earlier to it. It takes me 10 minutes or so once a month to make up my supplements using bulk mixes , and I'm good for the month. Once dialed in , it has been rock solid numbers every week without changing a thing , and ZERO maintenance.
By far the best change I have done in years of reef-keeping . Cost wise is very minimal I find on 400 + gal system , in comparison to ease of use. I'm guessing $10 - 15 a month at the most , which in my opinion , if that seems too much I shouldn't be running this size of tank in the first place.
HTH