Downsizing from our big 5-bedroom house to one without stairs and lots
of grass. One we are looking at has a largish (20'x12')"koi" pond with
waterfall. Looks professionally made and was operating yesterday. The
water was a very dark green and opaque and I couldn't see the bottom.
Since I am now 70 (good health) but with a cranky knee, am I asking for
trouble? I have yearned for a pond for a number of years, but since
this move is mostly motivated by the desire for less maintenance and
physical labor, I'm worried.

I live in the Phoenix area so cold is not the problem, heat is. The
entire pond is covered by a lanai with sun screening.

Chip