Well I'm finally get around to getting my pond put in (it's a preformed plastic liner type). I'm at the point of adding my pump and filter. I bought a used Little Giant stream and waterfall pump from a guy for a good price. He was using lava rock for his filter. The lava rock is...
t5ho / t5no / large lava rock / driftwood
Lava rock $65/all
(measurements are approx inches and on the small side L*W*H), used them in my 90G, but I'm going more dutch style so no room anymore for the rocks.