*YEARS* ago on my last pond ( which was fiberglass) I just used a swimming
pool sand filter & vacuumed the bottom. In Spring, I'd empty the thing out &
clean. tossing crud out.

NOW, this pond is twice as big (vinyl-type liner) & deeper.. I saw where
some use the vacuum type thing to suck up the crud,( the is ONE advertised
that it doesn't add water to pond,, but uses water pressure to 'remove'
gunk....yes, I know there is one thread started on vacuum thingies)...
but you guys totally EMPTY your ponds to remove the gunk??? big ponds
3000 gal ones?? on, where do you put the fish??? ( this time I don't have a
separate holding pond........ guess I could borrow the horses' water
container??? 100 gal