pretty sure like other sps members here, their tank would consume about 1dkh every 2 hours and carx is the only way to keep up with the demand. my tank would consume like 4dkh every 6 hours. once you get to that level, you will understand.
*upfront cost: yes it is expensive, but it will offset that in the long run. i am running a geo 818 with a secondary 618, carbon doser, and kamoer fx-stp with pure limestone media.
*setting up / calibrating: no difference when you are dosing kalk. you are still testing alk and adjust accordingly. setting up a carx it actually easier than you think.
*biggest pro - you are no longer mixing/slurry kalk. before using carx, i was mixing and going through at least 4gal of kalk daily. it got to a point mixing became a chore. i was only able to dose kalk for about 8 months before i had to jump into a carx. media for carx will last longer and minimal adjustments are needed once you dial it in.
*biggest con: you will have low pH cause of the effluent, that is why i use a secondary reactor to offset that. people do still dose kalk ontop of the carx to get the pH higher. my tank is in the man cave aka garage so i have no issues with low pH.
what i did with demand with my sps dominate bb tank:
less than year - water changes
1 - 1.5 years - water changes + dosing kalk + amino acid dosing
1.5 years+ - no water changes + carx + trace elements + magnesium dosing + amino acid dosing
if you are relying on AFR as your go to, i wish you the best. i do not believe in one product that gives your tank all it needs.
in the end, carx with trace element dosing is the end game in this hobby. if you are at the level which
@derek_SR is at, its the only way. kalk can only go so far and has its limit on how much it can help before demand takes over.