I recently purchased a 50# bag of stock salt at Tractor Supply. <$5.00 for 50#. It seemed to work well for mixing in the water to transport fish. But I realize that not everyone will need that volume of salt.
A couple 1200 gallon tanks will go thru it like candy.
I am changing the way of dosing salt.
Originally, I was going to premix in a tank of water, then take salinity measurements and all that stuff. Another mixing tank will also take up room, then pumps, metering devices, conductivity sensors and all that other stuff.
Gravimetric with dry seems to be an easier way, at least for me. And it would all be overhead, so no floor space required. I can measure the water volume in the system within 1/2 gallon, worst case, so make up water and dry dosing should be quite a bit easier.
Just thinking out loud here.