Where can I purchase bags of aluminum sulfate for a reasonable price within 75 miles of Fort Worth? I need to apply close to 1000 pounds to clear a six acre pond with 8 inches of visibility due to suspended clay. Gypsum is cheap in 40 pound bags at any farm supply store, but I have not found alum in larger that 4 pound bags, and they are very proud of it.

Look in yellow pages or do a search on the Internet for Chemical companies that can probably supply alum in your area. Another possibility is to contact a local sewage treatment plant and find out where they get their alum from. It's very commonly used in the water treatment business.

I got 50 lb. bags dirt cheap in my area from a chemical supply company. Much Much cheaper than than the smaller bags you speak of.

Estes has locations in Ft. Worth and Carrollton. Ft. Worth doesn't currently have aluminum sulfate on hand, but Carrollton does - 50# bags (they can handle branch transfers). You'll need to check with them on the pricing, as freight-costs are major part of that product's expense.
Ft. Worth: (817) 284-9433