So, if that were my tank, I would take a razor blade to the back glass and then see if your kalk setup keeps up...unless you like the look of the pink back glass. Coralline is just such an alk sink.I kind of figured it was alot as I look at pictures of other reef tanks. Not sure why I am so lucky perhaps because I don't have much else in the tank to compete? It's a 150 tank but 75 sump so I'm estimating 180 total water volume.
I try to keep my alk between 9 and 10 but this is a combination of the kalk stirrer and manual dosing. Ph is between 8.4 and 8.5 after the manual dosing.
You could also let the alk drift down to the 7-8 dKH range. That might help with the consumption also.
Are you going to keep any SPS?