I've made 3 smaller "patio ponds" out of various materials that I have scrounged up. Depending upon the size of pond you want to create, some of these techniques may be useful to you. 2 of my ponds get dismantled for winter and the fish are overwintered inside the house in a large aquarium. My smallest pond is made from wood shipping pallets that I got from work and a shower curtain liner. I measured the liner and decided on a size and depth to cut the wood to. I built a basic solid box out of 2x4s that was approximately 2' tall and 4'x4'. I finished the top edge with a 2x6 and stained it. Each spring I go buy a new curtain liner and staple it to the inside edge. Add water and a pump and you're finished. The 2nd pond is built in a somewhat similar fashion, with lumber I repurposed after tearing out an old deck. I built 8 boxes (about 2'x2'x2') that served as the 8 angles of my octagon. I then attached 2x6s between the corners of each set of boxes, creating one large octagon. I bought a huge roll of the thickest plastic drop cloth I could find, lined the inside twice, and stapled the edges. The 8 boxes were filled with potting mix and planted with flowers. I added a pump and fountain, and it works great. Again, this gets dismantled in the fall, and the fish are brought inside. It's so shallow it will freeze solid otherwise. New liner every year, also. My third pond is built out of chunks of concrete torn out when we re-did the sidewalks. This one is permanent. It sits on dirt, so I did dig down just a little bit to increase the depth of the pond and also to get the lowest layer of concrete below ground level. I just mortared the concrete chunks together as I built the wall up to the desired height. Once I was close to the desired height, I put the pond liner in (yes, I actually spent money on a REAL pond liner. LOL!) and then placed more concrete chunks on top of the edges of the liner to hide it and give it a more finished look. I looked up a concoction containing yogurt and ground up moss on the internet, made it and covered the concrete with it. It's starting to grow a little bit, which gives it all a more weathered look. Add water, fish, and a pump.....Viola! Those are my creations! Other than the pumps, I really have a minimal amount of money invested in each. They aren't award-winning by any means, but I think they add a lot to my otherwise bare patio areas.

Yes, a small above ground pond would more than likely freeze. Where I'm at, it gets cold (below freezing), then it'll warm up to about 35/40, rain, then drop below freezing again so then we end up with ice everywhere.... This last winter was super mild and quite pleasant, but we go in cycles. We have mild winters then we have cold rainy ones, then cold snowy ones, then cold rainy ones, then mild...and the cycle continues. The nice thing about the location I've picked is that it will be somewhat protected from wind (which is what really gets us up here when it comes to things freezing!), it is somewhat protected from the rain, one side of the pond would be up against the house and the other side up against our porch which would be a bit of a heat source...I know not much but, but enough to help. We have some plants here that if you plant them out in the yard, even if you mulch them, they don't always return, but if you plant them up against the house, they get just enough eat to survive. Sooooo, I am thinking, considering it'd be fairly protected from the elements, if I toss a heater in, I might be able to keep it just above freezing. Plants I don't mind if I have to take them in, I can put them in my fish tank during the winter if there aren't too many. But I would not have room in my tank for pond fish and unless I build a separate mini indoor pond to use in the winter, I won't be able to bring pond fish in. I did consider the bathtub idea. I found one for $30 on craigslist, but the sides of it extend out a bit further than what I want so it would take up too much room on the cement. I'll keep my eye out though for something that might work. I did find a cast iron one but the guy sold it already :( Hubby wasn't excited about that anyways because he doesn't want a heavy tub to move to the backyard, hehe. Keep the ideas rolling! Once I get it done, I'll post up pictures, but it'll probably be awhile. I have summer classes starting in a week and a competition to prep for so I plan on spending the next month or two just keeping my eye out for super cheap items I can use, then after my competition I will see what items I have gathered and hopefully be able to put in the time to build it all.

I have seen the strap idea work on round structures. It's how they build wood water towers in NYC, just vertical wood planks instead of block. These towers are on top of many buildings there. I saw a temp pond made from very thin plywood so it would bend easy and steel cable. The water pushed out the walls to make the round shape and the steel cable kept it together. Worked fine. Weakness is created as you move from round to straight sides. And the longer the side the weaker. When you get to rectangular the straps are tight in the corners but in the middle of the long wall it's loose enough that you can even get your finger in between the steel and block. Shannon's pond is about 5' square. 9' long means less strength from the steel. Mind you this is all about degrees of strength. Just dry stacked and no steel might hold for some time. It's impossible to predict how flat your block is and how clean the contact surfaces will be and therefore how much friction there will be. That's the basic weakness issue in this type of structure, you're relying on a weak friction. I expect a dry stacked structure would be a 50-50 chance of holding initially. Some blocks will probably move some. As the structure gets bumped, water moves, temps change I expect it to deform more as time passes. No way to tell if it would hold 1 minute, 1 year or 10 years. The nice thing about Shannon's strap idea is it should stop a violent failure...blocks shooting out and maybe hurting someone. Burying the first course could help, but I doubt it. Depends on the soil but I'd expect good friction there already plus the weight of the upper blocks. The problem with dry stack is that the joints don't have a lot of friction so each block can slide a bit. The blocks don't have a lot of contact surface area. The blocks aren't all exactly the same size or perfectly even so some will be loose. Putting the thin pavers in there only increases the number of joints which increases the weakness. Gluing the courses together would help but I don't know of any glues that could be dissolved for the tear down. You could use a lime mortar mix and build with a traditional mortar joint. Lime mortar is an old recipe but it still used today. DIYer's often want strong, super strong and super duper strong. Lime mortar is weak. But that's also it's strength because it gives instead of cracking which is why it is still used today for some applications. I suggest it here because there are so few options. It would greatly increase the friction between courses and lime mortar is easy to remove. It's almost like chalk. But you'd still need the threaded rod or straps to help the corners. Another choice goes back to Shannon's strap idea...you can greatly increase the strength...making a pond that would be very stable and last for 100+ years by making a round pond, if that's OK. The scary part is that it will not look like it should work. Here's the block pattern. Then the steel strap or cable goes around each course. You can use wood like in Shannon's image to keep the middle courses in place to reduce the number of straps to 2 like Shannon shows on the top and bottom course. You could use the pavers then too. Using parts of old pallets would work for the wood. The other scary part is that you do not want to stagger the joints. Each block is exactly on top of the lower. I would use steel cable and a turnbuckle so you could tighten as needed. You don't want the steel cable so tight that it moves blocks. Instead let the water push the blocks out into the cable. But it has to be tight enough so there's no gap between the corners of blocks that are touching. Round also gives you the most water volume for the same amount of materials.

Maybe make a wood or block frame of some sort around it with landscape fabric as a "liner". The fill it with sand. You could make it "snug" fitting or slightly larger add some top soil and do plantings around it.