"Lee B." wrote in message
...
According to the "experts" you should have one 4" gravity fed drain every
10'. To work effectively, you should have a 1/2" drop per foot to the
drain.
Don't forget the anti-vortex cover over the drain, or it will merely suck
the water from directly above instead of being forced to draw the water
from
the bottom. 4" drains are preferred because they will not clog as
readily,
and if an inquisitive fish *does* go down the drain, it has room to make
it
to the settling tank on the other end without getting stuck. DIY types can
jerry-rig a bottom drain very easily using toilet bowl flanges (one below
the liner and one above) and terra-cotta "bowl" type planters for the
anti-vortex. If you can get the type of anti-vortex that has an airdome
attached, it will accomplish two things: a) it will aerate your pond for
you, and b) the rising bubbles actually draw the bottom stuff towards the
drain.
snip

My BD is a DIY...although I never put my DIY diffuser on last year. I think
this year, I will be doing some swimming to get that done. Right now, I have
the pump running to see how it works to remove leaf matter. So far, not so
good without the diffuser.


--
BV.
www.iheartmypond.com