Thanks. I began to think something like this was happening when we
investigated the filter box yesterday and found it so gunged up. We
cleaned it, and it might be just my imagination, but I think it might
be a bit clearer this morning. The filter in the past has needed very
little attention. We've inspected it once every couple of weeks, but it
hasn't usually needed any attention at all. It's been like this for
nine years or so. The sponge filter on the other hand has needed very
frequent cleaning. Weekly, or more in the summer.

Obviously the pump cage has changed the system somewhat. So the so
called "lower maintenance" that the pump cage offers merely swaps
cleaning out the sponge filter frequently for cleaning out the filter
box frequently. Well, there you go!

I think we'll persevere with it a bit longer and see what happens. See
if it is a better system. The main advantage I can see is that you
don't release half of the muck back into the pond when you try to
remove it for cleaning, as you do with the sponge filter. I think
there's a bit of a backlog of gunge from when the old pump was on a
go-slow without our realising, see what happens when that clears.

Thanks again.


--
Jan-I