Nice to see Sanitred is #1 in the Google search! I wish that had been the case 6 years ago when this thread was started! The thing with Permaflex is that it's really thin - strong, but thin. I did two coats but it doesn't have much of a thickness. It's the liquid rubber (the blue stuff) that has thickness and stretch. The other thing is that what they say about the bonding process is absolutely true. At any stage (or age) Permaflex/LRB will bond with itself. If you follow the instructions this stuff will work. I speak from experience on that because the first install I did 4 years ago did not follow the instructions in one section (under the rocks on the waterfall side) and that section cracked this past winter. The rest of the pond which was clean concrete held up perfectly and looked as if it had just been painted when we drained and cleaned it. I like the color choices too! I went with the beige. The photo shows the finished re-hab from June. The *only* part that is new Permaflex is the floor (one coat) and the back wall under the waterfall and channel. Everything else is a 4 year old installation

I have a pond that is about 800 gallons. I don't have any kind of filter in it. Just alot of pebbles on the bottom and it seems to work. I also have a small waterfall and it seems to work just fine. I don't think i would worry about a waterfall filter until you found you needed one. I made the waterfall from a mountain of clay i dug out to make the pond. I did it in 3 sections. Each section you make you have to use a seperate piece of rubber. The top section is a small pool (about 5 gallons) that the water pumps into. From this the water runs over a lip and down about 4 feet of layered slate. It them dumps over another ledge and into another small pool (about 20 gallons). It them dumps from this pool into the pond. If you just keep your slate and stones on top of the rubber it shouldn't leak if you layer your rubber over top each other going down. If you want the ribbon effect of water running over the slate you have to put the slate under the cut rubber to stick out over the edge with the piece of rubber going over most of it. you cover up the visable rubber that's over the slate with rocks to hide it. You might have to put another piece of rubber under the origional rubber if the water is going to run backwards under the slate and leak out. I had to do this in one section only. All the other pieces are o.k. You can also get some foam spray stuff from the garden store that is suppost to seal these slate pieces together and that way the water won't run between the slate pieces. It would seal it i think. I hope this helps.

I was just thinking the same thing as chas045. Last winter was our first with our new pond. We'd just completed it in fall. We didn't know if we should keep the waterfall running over the winter, but before we could make other plans we got lots of snow & sub-freezing weather that didn't stop until there was ice on the sides of the waterfall stream. By then it was too late to drain the filtration system so we just continued to run it all winter, and there was nothing we could do about the ice build-up. Anyway, in spring we noticed the pond losing water much faster than normal. What we discovered was the ice (or combination of ice & dirt settling on the new waterfall structure) had cracked the mortar around the rocks that formed the sides of the waterfall on one side, right at the top, and also right under the waterfall box (see close-up pic). The dirt-covered structure in the upper right is the waterfall spillway. Ice formed mostly on one side, as you can see in the photo, and that's the side that eventually leaked. We are in VA so you could have it even worse in MN, even without your waterfalls running in winter. This allowed water to seep behind the rocks. Once it got behind those rocks, it made it's way down behind all the rocks on that side - between the rocks & the liner. But then near the bottom of the waterfall we had a steeper section & the water made it's way over the top of the liner & out of the pond. Once some of the rocks hiding the liner were removed, we could see where the water was running over the top. We never could tell it was leaking by looking around the landscaping there either, as it never appeared wetter than elsewhere.

I don't see where your water fall would spill from, although I suppose it doesn't really matter. If it fell onto that outcrop, it would give extra sounds although it would probably spill out the back so I suppose the fall is elsewhere. you never actually said how big the existing pipes are, but if they are 3/4 inch galvanized pipe, for example; that was probably too small for a regular modern waterfall anyway. I'm not sure that any of us is an expert on algae. I have a long stream and a skippy filter. Look skippy filter up. I am quite certain that my stream is my major filter. I get string algae, but find it generally useful. It doesn't cloud up the water; it just looks green. In my case, it is mostly in the stream. I occasionally remove it with a toilet brush to snag it, or just grab it by hand. People with the pea soup algae try all sorts of things and sometimes they work, and sometimes not. We occasionally have a poster named waterbug_guy. He has done lengthy study and believes that string algae fights off the single cell (pea soup type) algae. But of course, you have to have some to fight the other type. I think that there is general agreement that the UV tube device will kill free flowing algae. I have heard that the uv bulb needs replacement every year or so. You don't really need a filter without fish. Again: I never had a problem so am not much help and many who do, don't always get things solved. If it were me, I would go one step at a time and get a pump and flex tubing. First, I would quickly pump all the water out and clean the bowl with something and see if you can dry it out while installing your plumbing and spillway or whatever. Then I would fill and run it; scrounge up a few plants (hooked on or supported on something, or find a neighbor or store with a water lily to toss in the bottom) and see if algae forms. If you get pea soup that doesn't go away in a month, then get a UV tube thingie and see if that does the trick. You could look up 'trickle tower' as a filter device. It is a fairly new idea that I know nothing about. But again, I think it is more for preventing build up of ammonia or nitrates that can come from fish waste. No fish, no problem, I suspect.