"PM" wrote:

Hello PM

P Thanks Simon. Is bitumastic emulsion safe for fish/frogs
P etc? I'll give it a google.

Yep. Or at least, I've used it myself with no problem - leaving a week
for it to cure. I've also used Silicon solution (proprietry
waterproofing fluid - WaterSeal, AquaSeal etc) and no mystery dead
fish because of that. Again, a week's good drying time.

But with your mystery black stuff, I think bitumastic is about the
only thing that'll stick to it. Chances are it's tar, or a dirivative
(like bitumastic).

P The only concrete sealant I've come across so far is PVA,
P and I don't know whether this is suitable for ponds...

Yep, another thing I've used extensively. Painted on to block, then
mixed with first coat of render (rendered block pond), two more
painted coats, mixed for final render, then two more painted coats.
PVA is great waterproofing, BUT it ain't a gap-filler really.

--
Simon Avery, Dartmoor, UK Ý http://www.digdilem.org/