Can't be arsed to start a new thread. Attempting a mod to my reactor to stop the pellets getting stuck up under the top, and promote more movement in the tube.
I put some shells in the bottom of the reactor and some very small pieces of pumice I collected off the beach a couple of months ago. They've created a raft that allows water to flow but not allow the beads to get stuck to the upper surface. There is definitely more flow around the beads down the bottom and I'd be interested to use some larger or heavier shells in future.