Do it slowly. with alk that high if you start adding a bunch of calcium it's just going to precipitate out all over everything and fry your pumps. I once had a similar situation and caused extra problems for myself when I started adding calcium to get the levels up, didn't see them budge - because it was precipitating out almost instantly - and made it worse by increasing my dosing rate of calcium even more to try and compensate. I didn't realize what was happening till my protein skimmer, return pump, and power-heads all failed in the same week.
My preferred method for correcting things when they get out of whack like that now is through multiple water changes with replacement water that has the correct ratio of calcium to alkalinity, and only starting to use a doser again when things are at a stable and desirable ion ratio.
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