Install a Bottom Drain
A bottom drain is an essential part of any koi pool and we always recommend using a large sump drain. You must first work out flow rate i.e. if pool is 2000 gallons, your turn over is once every 2 hours, this is a 1000 gallons per hour turnover rate. If flow rate is under 1250 gallons per hour you should reduce drain pipework to 3", as this stops the pipework acting as a settlement chamber. You then increase the pipework to 4" before entering filter.
When you install bottom drain and pipework you should secure this in place prior to pouring concrete base, as wet concrete will cause the drain and pipework to float. We always put dry concrete over pipework and partly round drain the previous day before concreting pond base.
