I'm thinking of incorporating an anoxic denitrification chamber into my new pond.
This would be a 500-1000 gallon chamber stacked with Cermedia 8x8x4 blocks in a loose open grid.
Flow through rates would be very low - such that the water in the chamber would turn over about once every 4 hours or so.
The bottom of the chamber would be sloped towards the egress pipes, so some level of automatic purging would happen, and minimal sludge would collect.
The output would go back into the pre-RDF chamber to mop up any nitrites that might result from incomplete de-nitrification. Given the low flow though and relatively calm conditions in that chamber, I could possibly even explore drip dosing of sucrose solution to aid the denitrification process.
Diagram attached. (Any thoughts on the constant flushing setup where water from areas where sludge might collect is directed back to the main pond?)
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Do you think I would be better off just converting the whole thing to a huge moving bed.
Currently the plan is a 500g moving bed + 2 large showers fed by a pair of modified zakki manifolds. The moving bed is the backup in case I need to reduce flow to the zakkis for night time operation. Not sure how amenable the new neighbour will be to the sound of rushing water.
Looks like the pond will end up being 15,000 - 20,000 gallons, filter included.