20 years! Impressive. I will have to change mine on a preventative
basis!

Our pond can run over safely and the pump is always on, so a continual
flow from the valve would not affect the fish, I suspect. I think the
flow between berm ponds, the waterfalls and the streams expose the
flow to air sufficient to clear most or perhaps all of the chlorine.

We had one episode when the return from a berm pond was partially
blocked and we had overflow for a number of days. The valve refilled
the pond on an irregular basis until I noticed the wetness on the back
of the berm. The water was much more clear! The fish were
unaffected. I think of that as an inadvertant water change!

Jim