Regular water changes are always a fine idea, but I wouldn't do them to correct calcium and alkalinity problems. In this case, I'd just let the alkalinity decline on its own, and calcium will also come down a small amount. Just don't dose anything until the alkalinity is down a bit.
FWIW, I recommend 125-200 ppm CaCO3 equivalents (2.5-4 meq/L; 7-11 dKH) for alkalinity. Forget the kit recommendation, it is wrong.
FWIW, I recommend 125-200 ppm CaCO3 equivalents (2.5-4 meq/L; 7-11 dKH) for alkalinity. Forget the kit recommendation, it is wrong.