On Sun, 24 Jul 2011 11:03:38 +0100, Amanda
wrote:

I have a waterfall, which flows into a small stream constructed with
rubber liner, that then flows into a small pond.

The pond liner is (I think) some kind of cheaper plastic looking liner.

I believe water is leaking where the stream liner overlaps the pond
liner, ie water is creeping back up between the two liners.

I was wondering what is the best way to make a seal. I know you can
cement rubber to rubber, but I'm not sure about rubber to plastic, I was
considering using silicone (normal bathroom silicone) as it seems to be
very sticky on both types of surfacea and I already have a coiuple of
tubes, but I wonder if this could have harmful chemicals for the fish.

Any other things I could use?

(While writing this, I just realised that aquarium sealer must be safe,
but would it be flexible enough?)

Assuming that the "rubber" liner overlaps the pond liner and that the
pond liner is higher than the level of the pond, water should not flow
upwards back under the stream liner and you may have a leak somewhere
else - check around the pond at the level the water in it settles. I
would guess that the "rubber" liner is actually butyl (the best form
of liner as it can last up to 50 years if treated right). If the pond
liner is "cheaper" then it might be either PVC (10-15 year lifespan)
or polyethylene (3 years at most). If it's polyethylene then it would
be as well to drain the pond and replace the liner with PVC or butyl
as a first step.

I suggest that you buy a pond repair kit (or just the adhesive if sold
separately) from your local garden centre. The adhesive is made to
stick liner together.. You will need to drain the pond to below the
level of the join, and allow the area to dry. Then fold back the upper
liner and clean both faces thoroughly. Finally wipe with mentholated
spirits. Apply the waterproof adhesive to both surfaces and as soon as
it feels dry to the touch press the surfaces together and smooth
carefully to remove any air bubbles. Apply a weight to the join and
leave to fry for the amount of time specified on the tube/kit before
refilling the pond.

If, OTOH, you find another leak, it's a patch job (patch material will
be in the kit) but make sure that the patch extends at least 2 inches
all round the tear.

Cheers
Jake
==============================================
Gardening at the dry end (east) of Swansea Bay
in between reading anything by JRR Tolkien.

www.rivendell.org.uk