"Anon" wrote:

I've recently bought a pump and biofilter for my pond. The pond is about
1400 imperial gallons and is heavily stocked with fish. I've positioned the
biofilter above the waterfall which is about 6ft above the water level and
about 10 metres away from the pond, the waterfall lip is about 18 inches
wide and is connected by a stream. I bought a Yamitsu 12000 solids handling
pump and a Green2Clean 24000 filter which, in theory should both be more
than adequate for this pond. Unfortunately when the pond was built they used
18mm internal diameter pipe to supply the waterfall from the pond. As a
result the flow at the waterfall with this pump and biofilter is not much
more than a trickle. I have run a 38mm pipe between to test if this makes a
difference and it is much more acceptable. However, the original pipe is
buried in the ground under the pond, stream, rockery and waterfall, and
changing it for wider pipe would be an absolutely mammoth task that I would
prefer to avoid at all costs.
My question is: would getting a more powerful pump fix this problem? I have
had differing advice at several pond stores. Some say that the more powerful
pumps produce massive volumes of water but not a lot of pressure so would
still struggle to force the water up that diameter pump. Although at one
store I was told that narrower pipe is better as it creates more pressure
than wider pipe.
I would very much appreciate your comments and advice.
Jay.

A bigger pipe is ALWAYS better than a small one. Even if the pipe diameter
is greater than the output diameter of the pump this is preferred. A bigger
pump will produce more whoosh, but at this point I would say the law of
diminishing returns kicks in. You can only push so much water through a
small diameter.

Does your pipe have to be in the location it is now? Perhaps you can replace
the pipe in a different location? Just disconnect the old one and pretend it
never existed. Alternately, can you run an additional pump and pipe to make
up the difference?

San Diego Joe
4,000 - 5,000 Gallons.
Koi, Goldfish, and RES named Colombo.