only snails, hermits, and worms at this point, and for about 4 more weeks. The lfs should give you credit against a future purchase. An ATO unit to stabilize that salinity: hand-adding water won't suffice long-term. An alkalinity test kit. Salifert brand. hit 8.3 dkh.
Hey, we all started like this, with a whole lot to learn and an lfs trying to sell you whatever they can. They're good guys, but they may not know your situation.