I'm using a product called Dowflake. Its Calcium Chloride. It comes in a 50 lb. bag. If they have it at Univar I'll split a bag with you. I'm very familiar with Univar. They are a chemical distributor.
I bought a bag online but the shipping was more than the material. I'm glad someone found a local supplier. Its sold up north at Home Depots for side walk deicing. Please get me the trade name of the material that Univar carries and I will check it out and see if its OK for aquarium use. The potential problem is contaminants such as phosphates.
Gary
125 SPS, 75 gal. LPS/softie reef, 9 gal. Nano