tank is way to new to be dosing, 380 isn't that low, it may be your kit isn't that accurate. also if your tank is 30g or lower water changes should take care of all elements. you have nothing in your tank that will suck up cal. it could also be your salt mix giving you low cal numbers but more than likely it may be test. having two diff brand kits helps get a good idea on levels. also your tank won't cycle without something putting waste in system like a fish, so until it has livestock you won't have a cycle per-say

what is your tank volume