Do I Need To Seam Some Pond Liners Here?


Ax01

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Ok i need to sweep up some small pebbles and tamp my dig, then lay down geotextile and liner and i can start rocking the pond. i have a question about my pond liner(s) and seaming tho. my pond ecosystem will use 2 liners - a large one for the pond and a small one that will be used for my biofall/waterfall. Do these 2 pieces need to be seamed together? Or can i just drape the liner for the biofall over the pond liner and rock on it from there. i don't want to worry about the water getting behind the liner(s) and under the pond. Do i need to seem or is it fine to drape/overlap them?
 
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You need two things to happen - the pond liner needs to come up UNDER the waterfall liner a good distance, and the bog liner needs to come DOWN over the pond liner a good distance. How much depends a great deal on the exact construction of both, but basically you want to be sure the bottom liner can't fall down, and the top liner has enough overhang that water won't wick up. Simply placing two liners in a plane with each other will lead to wicking, if that makes sense. In any case I think the bottom liner coming up far enough is more important than the overlap on the waterfall liner.

Our overlap is about 3 feet on both liners, but we have a big waterfall which leaves lots of room for the liner to come up from the pond - which is why there really can't be a prescribed amount.

Some people do use adhesive to "glue" the two liners together for extra security - not a seam exactly, but more of a bond. PL roofing goop is one product that is often mentioned for this purpose.

Hope that helps! These things are often harder to describe than they are to actually do!
 

addy1

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My stream and a few of the waterfalls are all draped, I made sure the pond liner came up at least a foot and the other liner laid over it at least a foot. I was dealing with a big slope so easy to have a good drape amount.
 

Ax01

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@Lisak1 - thanks! i had to look up the term "wick" and "wicking" b/c i didn't know what it means or at least in this context. i don't want water to get behind the liner esp. the pond liner b/c they are too short in their overlap/draping. i think i should have enough fish safe black silicone sealant to "glue" them together if needed. i wanna avoid buying roofing goop and any more stuff for this project as i already bought 1 time use times like a 3inch hole saw bit and adapter and channellocks and other stuff.

@addy1 - thanks! draping w/ enough overlap it is!
 
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I agree with the overlap methodology. When I added a bog onto my existing pond, i did just that.

Before adding the bog, my pond liner had already extended up about 3 feet under my existing waterfall. I laid my new bog liner over that, overlapping it about 3 feet. There is also an elevation difference between the bog and the level of the pond water, so any water would naturally flow downward back into the pond. I think any wicking between the liners is also prevented by the heavy layers of large stones sitting on top of the liners.

I didn't use any adhesives between the two liners, but you can if you feel the need. A lot of people have had good results with PL-S30 polyurethane based roofing adhesive. It comes in standard sized tubes you can use in a regular caulking gun.
 

addy1

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I have not had wicking issues with liners that over lap by a foot or so and going up in elevation. Did have wicking with a 2-3 inch overlap, one small pond with a tiny waterfall into the next pond. I ended up putting a bit of wire mesh between the liner and the edge = air gap = no wicking.
 
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I cant speak for every scenario but like Addy said 2 to 3 inches would be about the max I would ever expect to see water wicking between rubber folds. Rubber does not absorb water but its water that pulls its self up. When you stick a finger or any item into water you'll notice the water actually pulls up around your finger just a little its just one of those physic things.. Now there are also other concerns. If you have any plant thats hollow when it grows and or dies it can certainly absorb water like a sponge.
 

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