to get it up from 375 to 430? If I remeber right you will gain about 16ppm per 30ml (1ml per gal=16ppm incr.)you add of the calcium in your tank. The company does not recommend doing more than 1ml per gal/per day. so I would do 30ml per day of the cal until you are at the level you want (per mfg specification). How this works out in the real world I could not tell you, and I do not know of any side effects. but total you would need about 115-120 ml (at one time, not recomended) to raise you tank above the 430 range.
-John-