On Tue, 5 May 2009 12:32:27 EDT, "Rick Samuel"
wrote:

Yes, water changes at least once an hour, so I assume ALL the water goes
thru the biofilter, none bypasses and goes straight to the pond from pump.
Thinking of two 100 gal. Rubbermaid stock tubs as the bio. One stepped
down from the first, gravity flow. Seems as tho asking a lot of gravity,
thru 4" PVC connectors. The pump I'm looking at is a Sequence 750 series,
4200 with leaf basket, 2800gph with the head I'll have.

Niagara seems to manage well on gravity. ;-) Question is, are the bulkheads
big enough to allow the gph you want to pass thru fast enough? ~ jan
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Zone 7a, SE Washington State
Ponds: www.jjspond.us