Hi W,

I have two skimmers in my pond, but a lot of the time one will suffice
and sometimes I only run one of them. My pond has a 25'x20' oval where
the skimmers are and the skimmers are opposite each other (25' between
them). Because of the distance, if it's very windy in one direction,
the debris will blow to one end or the other and only one of the
skimmers will get most of it. In that case, it's nice to have both
skimmers available because otherwise the debris wouldn't get sucked up
until the wind changed. It's really a location-/design- specific thing
as to whether you need one or two.

My pond is exposed (no barriers etc., only a berm to block the wind).
If yours will have some wind blockage or if the wind direction is very
predictable, you can probably get away with just one skimmer.

I have one 3" bottom drain in the low spot of my pond which goes to a
bio-mech filter. I don't know why you'd need more than one drain in a
pond that size. Do each of the drains get plumbed to the same filter?

Dave