I'd like to know some details if you have one - even if you aren't using it for your ducks. I still kind of want to build one and was looking at skippy filter info today and while out today, we check out HD/Lowe's and DH said he'd rather just do a preformed liner, get a smaller one or a nice pot/planter that's big enough to use as the filter. Lowe's had 91 gallons and smaller. HD had a few larger ones, but nothing that was easy for me to see. If you have a preformed pond... 1 - how big is it gallon wise? 2- what are the rough dimensions of it (length/width)? 3 - how deep is it at the deepest spot? If you use your pond for ducks 4 - how many and what kind/size ducks? 5 - how often do you have to 'tend' to it and what does that include? 6 - how often do you need to change out the water? 7 - how do you drain (if you installed one, what's your set up)? 8 - what type of filter do you use and how does it work? If you happen to have a pond with a pond liner that your ducks use... what type of liner and how thick - saw some 45mil EPDM (EDPM? whatever - that one) and some pvc ones that were 20 and 22 mil. Duck nails an issue if you provide a way out that doesn't put them in contact with the liner? If I build one that way, I'm thinking of using landscape timbers, so it would be square/rectangle with straight edges.