Hmmm...I'm getting more hooked by the minute :-) Having read your
replies I am starting to thing about draining the pond and giving it a
once over...I have a free weekend this week so why not. I would be
good to know whats under there, the water is pretty clear now and there
appear to be some nicstuff under there. It would be good to sort it
out and arrange everything as I want.

Any advice before I get stuck in?

I would like to keep Koi but by the sounds of it I need a bigger pond.
By gardern which is 100' X 25' is big by London standards by probaby
not big enough to allow for a pond big enough for Koi + my better hald
wants a new kitchen...priorities