Thanks Archimedes, thanks Michey. Archimedes its framed in treated 2x6s stood on edge that are attached to treated posted sunk in the ground below the frost line--you then bring your rubber liner up over the edge of the board down to the outside of it and then screw a treated 2x4 on the outside to pin the liner in-between the 2 boards (make sure the screws don't go thru both boards and pierce the pond side of the liner) Skippy's filter website explains how to do it with pictures--that's where I got the Idea although I beefed it up by using treated 2x4 posts instead of attaching the 2x6 to pieces of conduit driven into the ground like they wanted (I did drive some conduit in between the posts to help hold back the water weight pressing against the 2x6) also the Skippy site wanted to pin the liner with pieces of scrap lathe boards but I used treated 2x4s screwed flush with the top of the 2x6 so I had a double wide board that I could screw my top treated 2x6 (the board you see with rocks stacked on top) finish board. The finish board was my Idea to hide the liner and provide a place to stack rocks or just to provide a more finished look to the perimeter. I haven't regretted using Skippy's perimeter board Idea, it has several advantages over just a dirt perimeter collar 1st, once you get it leveled out and attached to the post it shouldn't move or sink like a dirt collar may do as the dirt settles. 2nd, its a sharp delineation between the pond edge and the surrounding yard--only 2 boards thick instead of the 12 to 18 inches I've seen on most pond dirt collars --I like this on the side facing my patio as you can literally stand right on the edge of the pond instead of back a foot or more.3rd its an easy way to gain shallow plant shelves or large lagoons without digging since you just pull back from the edge of your dug area to where you want the pond edge to be and mount the top edge of your perimeter board (leveled) 7 to 9 inches from the ground surface and shazam when you pull the liner into place and fill with water you now have 7 to 9 inches of shallow plant shelves. keep in mind if you want to go taller than that you will need a taller treated perimeter board 2x8 to 2x12 will work but then you will need more posts to hold back the additional water weight which can get considerable the taller your edge gets. That being said about the advantages there is one disadvantage I am going to try to rectify on my next pond--that is that a treated board doesn't CURVE which means the perimeter of your pond built this way has to be angular which doesn't look natural--I rounded right angle corners by placing large rocks in the pond corners to make curves and then filled up between the curved rocks and the board corners with large gravel to soften the edges into something that looked more natural. I plan on trying to use manmade plastic boards with more posts to force the perimeter to curve in a large gradual curve--plastic boards arnt as rigid as real wood and the next pond is gonna be twice as big so hopefully the perimeter will curve like I want (probably stack 3 or 4 plastic 2x4 up to get the height since 2x4 plastic boards will bow easier than 2x6 plastic boards would)
