i sort of recently (6 months ago) took down my ca reactor as i was having elevated alk problems which are dangerous when using the full zeovit method.
zeo doesnt recommend an alk pass 8, with 7 being more ideal. with my ca reactor shooting it up to the 9's...it became more trouble than it was worth.
i now do large water changes (70 gallons per week) with natural sea water (nsw) and tweak my calcium with kent's turbo calcium and alk with seachem reef buffer.
yes, there are 'cheaper' ways of adjusting ones ca and alk manually but for how precious my time is...i am happy to spend a few extra pennies.
ca reactors do have their place, dont get me wrong...esp if one doesnt have access to nsw.
since dropping my ca reactor...coral growth has really taken off...FINALLY!!!