We are starting to plan a 610 gallon pond for next year. Aqadvisor isn't really helpful for our stocking because we'd like to add koi and they aren't in their database. We are in southern Indiana so the fish will need to be pretty cold hardy. I do know that goldfish do fine through the winter here but how will koi hold up? We were also thinking maybe dojo loaches. How will they hold up? I'm assuming I need to keep the surface from icing up so can I use a stock tank deicer for that or is there something else that works better? I haven't started looking at filters yet because I wanted to settle on stocking first so I know what I'm looking at for filtration but, in my tanks, I try to overfilter by double the needed amount so we're probably looking at around 1000 gallons. I have a small pond, about 80 gallons, with a waterfall but I tear it down in the winter and move the fish inside so I don't have any experience building to overwinter them outside. Will we have to set the pond in the ground or would it be fine sitting on top? I'm not worried about the stock tank not holding up if its on top but, I'm a bit worried about the fish needing the insulation they would have from the dirt if it was set in. Any suggestions or help is greatly appreciated.