I am planning on building a 1250gallon pond and want to have a few koi. My plan is to run a 3inch bottom drain to a 55 gallon barrel burried so the top is at water level. i'm trying to figure out the best way to turn the 55 gallon barrel into a filter having a submersible pump in it sending the water down a waterfall to the pond. I know the best solution would be to get a out of pond pump but i do not want to deal with that option. Will post a drawing later tonight. Please post ideas for the filter