Also note that the same 20 feet of pipe will provide
over 20 sq feet of execlent selfcleaning biological
filtration. Just bury most of the pipe below the
water level of the lowest pond and you will have
no problem.

Howard

"Rod Farlee" wrote in message
...
"BenignVanilla" writes:
So 4'' for my bottom drains, skimmer, filter, all runs?

Note that 20 feet of 4 inch pipe holds 131 gallons of water.
That's as much as three 50 gallon barrel filters typically hold.
If this is above the water line of the pond, and if it's a small pond,
it'll lower the pond after the pump is turned on. And if power is
lost, it'll drain back through the pump and overflow a small pond.