Actually, lava is what i used to use when i first started growing years ago, but havent been able to find any smaller than about 3/4" and larger. I tried breaking it up into smaller pieces, but took forever. I havent tried very hard to locate it in smaller sizes. Then when i see what everyone else is using, i didnt give it another thought. Ive been using a mix that is 40% diabase granite, 40% haydite, and 20% pine bark. I really like it, but cant find the granite in small pieces. So, here we are. Thanks alot for the john deere numbers. I actually have one here in mooresville, and its pretty large, so they should have it. Thanks again for the feedback.