Fair enough... but you should of added that your water doesn't contain
chlorine (or other), deadly to koi.

Small amounts of chlorine are not a problem.

I use a slightly different scheme, a 1/2 gal/hr drip irrigation emmiter
into my filter, thus overflowing 12 gallons a day. My vege garden is
downhill from my pond so I just move a hose around to use the water.

I'm happy with it. Pond always full, water clean and I use the water
twice :-)