Negative edge challenge

[old-muel]

 

[old-muel]

Doing a negative edge so my new pond I'm creating shares water with my existing pond, of course made the rookie mistake of cutting the liner when doing first ponds' edges so I've barely got enough to make this work but I think from testing thus far that it will - except I'm having encountering a problem- when shutting the pump off the water level drops to where it should (I understand the water in motion stuff) but then doesn't completely stop (keeps draining below level of wier). It's obvious now I've thought about it what's happening- the creases/folds in the liner are acting like straws and creating a syphon & draining the top pond when the pump turns off, an easy solution I can think of is to plug the few spots with some dabs of silicone, my liner on the old pond is PVC - will silicone play nicely with PVC does anyone know? Or any other solution?
Thanks

 

[GBBUDD]

Doing a negative edge so my new pond I'm creating shares water with my existing pond, of course made the rookie mistake of cutting the liner when doing first ponds' edges so I've barely got enough to make this work but I think from testing thus far that it will - except I'm having encountering a problem- when shutting the pump off the water level drops to where it should (I understand the water in motion stuff) but then doesn't completely stop (keeps draining below level of wier). It's obvious now I've thought about it what's happening- the creases/folds in the liner are acting like straws and creating a syphon & draining the top pond when the pump turns off, an easy solution I can think of is to plug the few spots with some dabs of silicone, my liner on the old pond is PVC - will silicone play nicely with PVC does anyone know? Or any other solution?
Thanks

I'm not a fan of silicone . It constantly leeches and as it does it dries out. Starts to loose its grip on what ever it was called to. I've seen this time and again. Now polyurethane caulking is another animal as is buttyl but I do not know of any buttons that are fish friendly.
So the pl series of roofing caulking is amount my preferred caulking.

 

[old-muel]

Thanks for the reply. Here we can get "aquarium silicone" that I didn't think leeched anything but yeah silicone in general doesn't have great adhesive/bonding properties I know what you mean.
Is it loctite pl roofing caulking,?
Says low VOC's, does that mean it still offgasses some VOC's , is this stuff fish safe??

 

[GBBUDD]

pL does not have a fish safe labeling , but after using all kinds of caulking's in the pond I'm leaning toward this is more of aquarium closed loops system concern. I have 5 waterfalls and a lot of surface agitation if it's even been a problem it has never showed it's self. I think as long as you stick with a quality caulking / polyurethanes. youll be fine