What I do is run a continuous trickle thru charcoal to remove heavy metals and chlorine and have the overage go out thru an overflow pipe. When I drain all my settling vortexes in the morning, the pond goes down about 4 inches. By mid-day it's back full again from the trickle and ready for the evening routine.
I;m convinced from decades of study that if we were to graph water quality,
it's better from a koi's point of view to have it flat line consistant than it is to have peaks and valleys of good and well, not so good.
