We belong to the lazy school of ponders.
When we were running our stock tank as a mechanical/bio
filter we cleaned it once a year. 150 gallon stock tank, 50 yards
of vinyl screening. All the muck in it smelled river water sweet.

With our reduced stock we run the stock tank as a veggie filter
with water hyacinth, then the water goes over a waterfall
planted with watercress.

kathy :-)