jim wrote:

I have 2 x 24v ones on my pond and I had the same problem, that is until I
went to a supplier and bought larger filters, my filters are roughly 200mm
long and about 100mm square with a hole in one end about 25mm diameter but
not all the way through the filter, in the hole goes a pvc extension pipe
that goes into original hole of pump and the filter pulls up over that. I
normally now clean my filters about 1-1/2 to 2 weeks and longer in winter,
the filter pores get clogged normally and a little bit of stuff on the
bottom of the filter that is on the bottom of the pond, that is why you
don't see anything, hope this helps with your problem.

Beauty, we have the same thing. I just stood everything on a couple of
bricks to ensure it was off the bottom. Seemed to need cleaning roughly
monthly.

Finally died after 3-4 years.