Planted Tank Enthusiast
Join Date: Jul 2014
Location: California for school, Arkansas for home
It depends on the brand. I use Instant Ocean Reef Crystals on my reef tank, so here's my calculations:
.5 cups sea salt per gallon for 1 gallon of saltwater (1.025 SG)
x~=~.496 cups for one gallon
4x (the amount of salt for 4 gallons)=1.984 cups of salt.
However, you may use a different brand. Therefore the amount of salt you'd need would be different. Grab a cheap hydrometer, and start mixing. Be warned, that some hydrometers need to be kept at certain temperatures to be accurate.
May I ask which fish you're acclimating from brackish to freshwater? Some fish live in brackish-saltwater that should go to saltwater later on. Others live in brackish-freshwater that should really be freshwater. Still others need to stay in a brackish environment. 1.017 is a really high salinity, especially for some brackish species, and you'd hate to accidentally kill the fish if it was a brackish-saltwater species, right?
So many fish to keep, not enough aquaria.