Upside down sand beds

[Rikko]

That defeats the entire purpose of a DSB and plenum then? I'm still in that camp that wants sand beds to be anaerobic.. Maybe I'm old fashioned.

That does remind me of King Ed's anemone/cube tank in the salt room. If you look at the sand surface you can see a few 'geysers' where it looks like water is returning. I've never really looked to closely at their plumbing but it appeared that's how they run it. I should ask Robert about it tomorrow.