Sustain, yes. Depends what size volume, and what's in there really. My 120 lps/softie dominated tank (below) would chew .4 alk/day. If relying on biweekly water changes alone, That is Way too much swinging for euphyllia to Thrive in. It has a negative effect on growth and color and coral health in overall.An LPS heavy tank can also "sustain", even thrive, with no dosing with regular water changes.