Hi Steve, my current pond construction has 4 pumps in the design for circulation and one trash pump to empty the sump that the filters empty into, so I believe in redundancy. I am also running Sequence pumps and they have 1 1/2" outputs but you put a simple adapter from 1 1/2" to 2" right out of the pump and then everything else is 2".
On the bioreactor this is a link to a commercial unit but you can easily make one:
http://www.aquaticeco.com/index.cfm/...etail/iid/7831
Here is a simple line drawing of what I made for my indoor system out of a couple of 55 gallon barrels:
Here is the link to the slotted pipe:
http://www.aquaticeco.com/index.cfm/...etail/iid/8550
Bioreactors or aerated K1 / Kaldness chambers are very efficient and there is 0 maintenance - I love mine. In the new pond I will incorporate a larger version based on William Limm's Wave 36 settlement chamber like the attached.
Rick