Originally Posted by zad2110

Hi,
I am fairly new to ponds and fish keeping. My step father and I built our pond two summers ago and last summer it started leaking and we were unable to find the leak. This spring or summer we are planning on completely redoing our pond and try and do a better job of making a filter. We plan to put in a bottom drain at about 3 feet and we plan to have about 1500 gallons total in the pond. We have a pre-filter box with some filter media to keep leaves and bigger stuff from clogging the pump. I have been watching a lot of videos on DIY biofilters and would like to know how big of a bio filter we would need to make for this size of a pond with around 8 goldfish and 3 koi. (i do not need my water to be extremely clean or anything i just want it to be better than it was last year when we couldnt see 1 foot down for most of the summer) My original thought was to make two filters from big flower pots and position them above where i want the waterfall and then have them run into the waterfall pond before going into the big pond. Any advice I can get would be greatly appreciated. Thank you very much.