How much Ca+ to add at once?

[danny zubot]

I was slackin' on my diagnostics for a couple of weeks and when I finally got around to it I noticed my calcium was really low, 260ppm. My Alk was about 3-3.5 Meq\L which is a bit low too. I've alway dosed pretty high to adjust Alk with no ill effects, but how fast should I raise the calcium per day to get back up to par? I usually keep it at about 380-400ppm and 5-6 Meq\L of Alk. Are these good levels for a mixed tank? (54 gallons)