IF you mean perlite when referring to sponge rock, I found some truly coarse, it is called "chunky", perlite, but it comes in a 4 cf. bag. I have a nice equipment shed and that's where I store a lot of my 2-4 cf. bags of stuff. I store my Douglas fir bark and horticultural charcoal at one end of my orchid greenhouse, under shelves. Because of fans and heaters at that end, I don't put plants on the shelves and thus the bags stay relatively dry.
I would often go though those 12, 4 qt. bags in a couple of hours. I use a lot of orchid mix and every time I get a new batch of orchids, typically 50 at a time, they will all be repotted into 5" mesh-pots. At least most of them will be. A few that are sub-compact/miniature might go in small hanging baskets or 3 3/4" mesh pots. Regardless, that takes a lot of mix! I have 60 new plants that are now in their two-week quarantine, and they will all go into 5" pots at the end of next week.
Bert, remember to get you some sort of storage/equipment shed when you move to Corinth. It will come in handy!
