Don't forget about a local Georgia company that supports the club, has allowed the club to visit their facility AND produces a synthetic salt. Seachem Vibrant Sea mixes quick and clean. I've let it sit in a 65 gallon barrel with no pump for 2 weeks and there was zero sediment.
It's stable and consistent - and again, a local company.
It's also concentrated - it does take less actual salt by weight to mix up to the same salinity from other brands I've used (this is the only synthetic salt I've used BTW). 1kg mixes up to about 31 liters at 1.025
www.seachem.com