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Pond lining question.? Answered

The moulded liner in my pond has given up - it's cracking faster than I can patch, so I'm going to re-line it.

I have a suitable flexible liner, but my question is:

Should I rip out the existing liner and line from scratch, or should I fit the liner inside the rigid liner?

The latter will be easier, but would the former be "better"?



6 years ago


When I was making my diffuser, I layered some foil over the container. Unfortunately, I am not gentle enough to keep it in one piece and so it cracked. I decided that two layers would better than one and so, if the top broke, the bottom would be there to protect it. If the bottom broke, the top would be there to keep it from showing through light. I think the same ould work for your lining.


6 years ago

Just a thought- assuming the moulded liner is a thermoplastic, you could potentially heat/soften the edges with a paint stripper heat gun, propane torch, Kitewife's hair dryer etc. and roll them under to keep the sharp cut edges away from the new liner?

Oh, and that would let me soften ans squish down the sharp corners!

And, if all I do is set fire to the old liner, I'll just rip it out and use the new liner from scratch!

A lot depends on what your pond is (or is going to be?) for - ie, 'goldfish', wildlife or is it just a water feature?

If the latter, then you might be OK just dropping the new liner on top, following iceng's advice.

However, you'll lose a (very small) amount of capacity and if this winter's as hard as last - or we get the 'mini ice-age' some are talking about - it'll be much more prone to freezing not only over, but, potentially solid (and floating a tennis ball doesn't always help that much anyway).

And similarly to Nostalgic Guy, I'd fear the old liner would continue to crack and pierce the new - especially as it "cracking faster than I can patch" suggests the possibility of settlement of the substrate, which would only be likely to get worse - though obviously the age of the liner will have a lot to do with the cracking.

And I don't like the idea of folding the new liner under the edges of the old - it's sharp stuff, and the weight of the water will (no matter how long you wait for it to settle inside the pond) eventually encourage the edges to slit the new liner.

But, whilst wildlife should adapt reasonably well to the those last two paragraphs (and your pond as it is), any 'goldfish' you introduce would probably have a far tougher time of it, and I'd strongly advise you to rip out the old liner and start again.

Depending on the size of your new liner and what you can get away with (expansion-wise) in the current position, you have an opportunity to create something much more visually appealing.

Do it the right way and take out the old liner. Reform the base material to support the new liner.

I'm not an expert by any stretch of the imagination but I have built a couple of ponds in the past.
How flexible is your new liner? I ask because none of the liners I have used in the past would hve coped well with some of the sharp right angles you appear to have in your rigid liner without forming some large deep creases; for this reason I would personally remove the liner & smooth out some of the sharper areas into curves rather than right angles.
Also I would be concerned that the rigid liner could pierce the new one particularly as it has already started to form cracks.
However if you do elect to keep the old liner I would certainly follow iceng's advice & make some holes to drain away any water that is in or gets into the inner liner.

The new liner is completely flexible.

I was wondering about a compromise, covering the sharp angles with an old folded towel?

Keep the old liner and place the new liner on the old one. once you fill with water the weight should form the new liner to the shape of the old one.


6 years ago

Keep the old liner as a strength support but put several dozen 10mm holes in to
drain smelly water accumulation over time.


Oh, that's a good thought...