Here in Pittsburgh, PA I can't get pumice with out great cost and just found out about the poultry (granite) grit last year. Also at the feed store they sold small bags (8 lb.) almost the same cost as 50 lb. bags. Also there are two sizes. small and large. The small is almost like sand and the large is like the size of large perlite. So live and learn, I buy the large only at $8.50 a bag. Seems to work very well so far for me. I have gone thru 4 bags so far. I like the weight of the product that holds the plant and roots together. At a 50-50 mix, what water I add seems to run right out. Just what the doctor ordered.
Stush