carey, the 2 little fishies stuff is good, but it can get a little on the expensive side. i would suggest saving 2 milk jugs, and making your own using BRS's stuff.
one zoa frag and a small gorgonian colony is not going to be very demanding.
i've kept large tanks just doing water changes- no added calcium, alk
, or mag. bear in mind i did 50 gallons weekly on a 400 gallon system though.
it was loaded with large ( softball and basketball sized) sps
only when i topped that off with a football sized clam did i see rapid declines in calcium and alk
, and then i went to the bulk additives.