"Oxymel of Squill" wrote ..
My little waterlily pond has a leak and I've given up trying to fix it.
Bob Flowerdew on the radio suggested filling in a pond with ericaceous
compost and planting blueberries, which like boggy soil.
Ericaceous compost from the garden centre is going to cost me a fortune. I
thought of filling in with builders' rubble to about a foot below ground
level, but presumably there's lots of lime in rubble.

Has anyone done this job? Have any suggestions?

Just drain and use a liner over the old pond to make it watertight again.
Probably cheapest too.
BTW if your existing pond is made with a plastic liner they always perish at
the waterline where UV light attacks the plastic so it's always best to try
to cover this bare liner with paving slabs, rocks, bricks etc. Alternatively
go to the expense of butyl rubber.

--
Regards
Bob Hobden
17mls W. of London.UK