Personally, I'd recommend buying RODI
and mixing your own SW
. Unfortunately, in my experience, many of the LFS
's mix their SW
at a lower salinity than most of like to use.... it's a way to stretch the amount of salt they use for a greater profit per gallon. Mixing your own is very easy in small quantities.... all you need is a small, cheapo power head and maybe a little 50w heater for a 5gal bucket. This allows you to use the salt you want, and mix it to the salinity you want to use.......
I know you want a challenge, but what is your end-goal with a 3g pico? With that
small of a tank, you are pretty much limiting yourself to maybe a small invert or two and a couple of corals..... no fish. To my knowledge, there are no marine fish that are compatible with a 3g tank. Even the tiniest of commonly available marine fish..... something like a red-banded goby, require a minimum
of a 10g tank. Personally, I'd go with something like a 20 long as your first tank..... plenty challenging enough, but opens up a much wider variety of livestock to choose from.