My only experience to date has been a preformed plastic pond. I now have enough epdm and ground to make a 10' x 20' free form with a nice waterfall. I would like to make it a Koi pond, but will be thrilled to start with comets. I have no idea what size skimmer, falls and pump to use and am looking for economical choice. I always have more time and energy than money. Would really appreciate some guidance and direction as I know most people keep going larger.