Yeah, I thought I remember it being super expensive, but wanted to make sure. If you can find a local fish store, SW
will be about $1/gallon, at least that is what I'm paying.
A 15g is a pretty small tank and I think the filter is enough at adding flow to your water, again, I'm not very sure so an expert would have to chime in. I have two HOB
filters and its enough water flow for me
, the general rule is 1lb per gallon.
A heater is also needed, a good temperature range is 76-80.
A liquid test kit is very useful but since you work at petco, you can just test your water there yourself =P.
You should rinse your sand first before adding it.