My prefilter only needs cleaning every 3-4 months.
It is a milk crate. Open end is down.
Exit pipe is up through center of bottom.
Wrapped with two layers of fiber glass screen
on four sides and bottom of crate.
To clean I lift out the whole thing and spray with
a water hose.


--
D. Wain Garrison
If you can read you can learn anything, for
there are those smarter than you who can
write, however, not everyone who can write
is smarter than you.
"John Hines" wrote in message
...
"Pierre de Ponthiere" wrote:


2) Pump in the pond
Pro's
Easy to install
No leakage below the ground level
Empty pond by pipe leakage avoided with a flottating switch in supply
electrical line
Pond waterlevel is not critical
Safe winterizing if all pipes (above ground level) are emptied before
freeze.

Con's
Pump hashs the dirt sent to the filters (New designs of Vortex pumps
reduce
the problem?)
Settlement vessel will not work properly -- install brushes in its
More maintenance: purge the settlement vessel and clean the filter
pump,
clean the brushes,..
Difficult to hide the bio filter (filter put on the ground)

Cons:

pump that can pull in solids (say up to 3/8 inch for example), will
pull
in plants and things like leaf stalks, and plug up the filter.

You can limit that by installing a pre-filter, but then you need to
clean it.

With a pump in the pond your gonna have to pull it out and clean it
periodically, at best every few weeks.

this has been my experience.