The only way calcium levels would really effect softies is if the levels were so low it was effecting the salinity or alkalinity. Don't bother feeding that often, will likely just spike your Ammonia/NO2/NO3 levels, which you want to be low or 0. They are "shrunken" because they are adjusting to the move, you have nothing to worry about will likely stretch out again in a few days to a week, smiliar idea as what happened with the GSPs. Your lights are fine, neither Xenia or GSPs need huge light output. Patience is a vertue lol.