An idea I have and surely it is not original is soaking it in a bucket with fertilizers. Stirring up the whole contents top to bottom a few times per day. This way the Florite soaks in all the ferts it is able to (search CEC). So when you reuse it there will be ferts inside the Florite.
Then just lay it out over the greatest available space to dry on a tarpaulin then store it sealed well in an appropriately sized bucket.
When I moved across the country years ago (had to move multiple tanks with flourite and eco complete), I drained the tanks, scooped all the substrate into buckets, drained the substrate best I could using my hands/scoop, and then just left them in the buckets. They dried. Nothing grew. Sat like that for years before being used again. No problems.
If you don't have the time to slowly dry and/or solarize the substrate, try baking it at 450 F for an hour, let it cool for a day, and put it into a sealed container to keep out dust and mold. A cheap rimmed cookie sheet works well for ashing/baking/mineralizing.
Last edited by flc; 01-02-2013 at 04:16 PM.
I've never done anything fancy with old substrate.
Rinse and dump into buckets. I do not seal the buckets right away (if ever) and the substrate may stay damp for quite a while. As long as it is clean that is OK.