I have a waterfall going into a small hard-sided pond, and had a similar problem. The falls are only about a foot high, and maybe 18 inches wide, but I would lose about 4 inches of water in 6 hours. The pond itself held water for days with no loss, but as soon as I turned on the falls...poof, water gone. It was driving me nuts! After doing a lot of reading here, and elsewhere, I discovered the concept of "wicking", or capillary action. Apparently, water CAN run uphill, under the right circumstances. If a waterfall liner runs over the edge of a pond and is tight up against the side of the pond, the water in the pond can be pulled up between the underside of the liner and the pond side, and be sucked into the soil. I found no other possible explanations, so I came up with a plan to possibly stop this, IF that was what was happening. First, I laid down a thick seam of expanding foam where the underside of the falls liner came over the edge of the pond. This was not intended to seal the seam so much as it was intended to just lift the liner away from the side of the pond. Once the foam was cured, I went back and "painted" the foam with a thorough coat of aquarium-grade silicone. I extended the silicone out from the foam about an inch in every direction, getting the liner AND the side of the pond. This WAS intended to seal every tiny crack and seam, and I did a thorough job of it. It looked terrible, but the liner covered all of it, and no one will ever see it! Then I trimmed off some excess liner where it draped into the pond, on the theory that the turbulence from the waterfall was causing the underside of the liner to be wetter, which could cause or worsen the wicking. (A shorter liner might "catch" fewer bubbles and splashes on the backside.) Then, as a final step, I added a bead of silicone to the underside of the bottom rocks of the waterfall, as a "drip edge". I put the bead about one inch back from the edge of the rock. I let the silicone cure for 24 hours, turned on the waterfall, and waited... Total success. It has been running for 2 days now, and has lost maybe a 1/4 inch...mostly from splash-out and evaporation I suspect. I know the drip edge is working because I can see water coming off the underside of the bottom rocks. I do not know if the shorter liner is having any effect. But the liner itself is most definitely being held away from the pond side by the foam, and the silicone is certainly blocking the crevices. Not sure what part is doing most of the work, but the combination is doing the job! What a relief.

For those who have mentioned grass (quackgrass, crabgrass, lawn grass) growth problems to this method, I have a miracle cure! Quackgrass has been the bane of my gardening existence. It has overridden my gardens and beat me many times. I agree with others, some grasses will come right up through that whole lasagna bed as soon as the cardboard/newspapers start to decompose. Actually, it will even poke right through it. Well, after re-doing so many beds, I finally found a product...it's Ortho's Grass-B-Gon. This product can be sprayed ON an existing garden (roses, veggies, perennials, shrubs, etc) and it WILL kill any grasses, but no broadleaves. It sometimes takes 2 applications, but I sprayed with a heavy trigger (pent up anger) and saw that quackgrass brown and dying within the week. New growth that comes up from roots underneath, give it another spray. I started this 2 years ago and all of my beds are nearly free of quackgrass. Since, it's in my lawn, it does get into the beds, but a confident squirt or two and I know that it can be stopped, or at least severely stunted. Grass-B-Gone can be hard to find, many Big Box stores don't have it. I found it at Walmart and I think I saw it for 1/2 again more at an ACE Hardware. I stocked up when I saw it last, buying about 4 spray bottles. Guess what? The problem is so under control, I still have 3 left from last year! It does say on bottle to avoid freezing, which I did not do, so I sprayed some grass the other day and am waiting for the browning. Lastly, this product will kill ALL Grasses. Therefore, I have decided that I am not going to plant ornamental grasses in my gardens. I love the ornamental grasses, but I don't want to worry about killing them when I have to treat an area. Here is a link that might be useful: Ortho's Grass-B-Gon Review

Lovely plants Dave. The rocks will hold a bit more heat in the afternoon and especially after dark when it was a warm/hot day. They don't look too big though so the length of time they hold warmth is probably pretty short, an hour or two. Some firs might object to the slightly warmer temps if they are surrounded by such rocks, but it wouldn't be a drastic difference. Thanks for sharing, -Will

When we can manage to find some time, we're going to run the rocks down the right side of the deck too. We're hosting a graduation party on the 24th, so we've got a million irons in the fire! Over the weekend I just happened to stop into a local greenhouse and they had 1 pot with 4 tiny "Oddity" Sempervivum - I was super excited, I've been looking for it! Now I have to figure out where it's going to go - probably down that right side when it gets done.