Great Stuff is a foam sealer that many folks use instead of the pricey black stuff. It's paintable. There are several formulas; you want the big gap filler.

That said, I blew a wad on Great Stuff only to realize that I was going to have to find another method because I had too many smaller stones and it was hole-ier than Swiss cheese. I ended up covering some pretty stonework with pond liner, siliconing it in, and covering with more rocks. I do have fun DIY-ing, but it can get expensive.

It's SO worth it when you finally get it right.

:^)

Sharon

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Hi Sharon,

Can you please clarify the foam sealer - is it silicone caulking that is used around windows (but I don't think it expands) or there is a product that sprays like foam and expands that people use to fill in cracks to insulate their homes? I want to make sure I get the right product. Thank you.

Angela, just ask at the hardware store for "Great Stuff". That's the name of it. It's different from insulation foam, but similar. It's waterproof and non-toxic when cured.

Sharon

you could always spend 200 on pond liner and end your woes.

great stuff will leak after a while due to animals and critters gnawing at it, i would shell out 200 especially on such a beautiful waterfall

Thanks, Sharpie. The falls in the pic is mine, and I've already used liner to line it. It wouldn't even fill up enough to run before that. The Great Stuff has been very useful though, in that it holds the rocks together nicely. Fortunately I had leftover liner pieces. I actually lined my whole pond, 30' X 15', for under $300 (plus the cost of a U-Haul rental). It's EPDM roofing. 2 years later and everyone seems happy in there.

Angela, I should mention that I did use silicone caulk in places where it would show a lot, and no, it does not expand. I just noticed you're in Canada. I checked and Great Stuff is available in Canada. Here's their web page.

Great Stuff Link

Sharon

Thanks Sharon for clarifying. I thought you were describing the product, I didn't know that Great Stuff was an actual name :o) I'll be off to Home Depot tomorrow. I actually have a liner in my waterfalls. The problem area is where the water falls off the edge of the rock into the pond. I don't think we built up the soil underneath the pond liner properly and now it is too much work to rip it all apart again so we have been using the foam to try and stop the leaking. This is our first pond and it has been frustrating. Thank you again.

You're welcome, and good luck. Post a pic if you can!

Sharon

First off, your local pond store is ripping you off like crazy. A can of black waterfall foam at home depot only costs around $11.00 a can.

Next, I am a firm believer in not using the foam to do anything more than hold rocks in place. I find that the foam eventually leaks. If you want to waterproof a waterfall, hydraulic cement works very well. I've used it now to build to waterfalls and have never had any leak problems with either one of them. Hydraulic cement can be bought by the tub or in bags at Home Depot and its not that expensive -- certainly less than paying $25.00 for a single can of foam.

is there a brand name of the hydraulic cement? Ive got my WF basically water tight with a combination of black and great stuff.

i noticed the black seems to expand more. I also found that instead of placing the rock and then foaming under it, if I put the foam on the rubber, then place the rock, then foam the back edge it seemed to work better.

also I will say the black looks better in the water areas but I havent painted the yellow yet.

if the foam dies on me in the future I will try the H Cement route.

I'm trying to make a very small waterfall. I see that I need the foam, which I got. Question: do you make sure that everything is dry before you foam? or can you foam on a wet surface?

It doesn't say on the can.

Thanks,

Liz

Three years ago when I was building my waterfall I bought the builders foam that goes between a window frame and the studs of a house. After I did I was told that I wouldn't be able to support fish in my pond since the stuff is toxic. Guess what? My fish, turtles and crawdads must be bionic because none of them have suffered from it. It is up to you but I wouldn't hesitate for a moment to use it again.

Here is a link that might be useful: My pond the way it was before the freeze.