I am of the opinion that one large, properly designed pump would cost
less to purchase and operate than several smaller pumps, particularly
when you consider the flow losses due to the plumbing associated with
multiple pumps (either each pump must have it's own filter, or each
pump must have a check valve to prevent backflow in the event it
fails).

I would take another approach. One of the 'authorities' tried an
experiment using an inexpensive aquarium air pump and an air stone.
He decided to see if this would provide sufficient oxygen for his koi
in the event the main pump shut down. It also had the advantage it
could be run off a car battery and inverter in the event of a power
outage. Total cost was under $15 for the pump and air stone.

He described hooking the thing up one evening, turning the main pump
off, then checking the pond every hour. Unfortunately he fell asleep,
only waking up after the main pump had been off more than 8 hours.
He was rather relieved to find all his koi were still doing well, with
no signs of any shortage of oxygen. Based on his report, this
approach should allow you to keep your koi healthy for an extended
period in the event of a main pump failure or power failure.

PlainBill

On 26 Aug 2003 21:36:28 GMT, (Scott Evans) wrote:

In a recent posting here, someone had lost their pump, and was wondering
what needed to be done to keep their fish safe until a replacement could
be found/installed. That got me thinking (never a good thing, but I
digress) a bit about how to minimize the short-term impact of a pump
failure. Going under the assumption that it takes a certain amount of
power to pump a given quantity of water, would it make more sense to
have multiple smaller pumps hooked up in parallel (with appropriate
back-flow check valves) rather than a single large pump? It shouldn't
take any more power to pump the water; the only additional cost would
be the initial plumbing and pump costs. It might be a worthwhile
tradeoff for peace-of-mind to put out a little more money upfront to
make sure that a pump failure won't take down a whole pond ecosystem.

Comments?

Scott