Preformed Ponds

I have always wanted to get into water gardening and ponds. I've always
rented and it never was an option. Now that I own my own home I can finally
do what I've always wanted.

I had a small preformed pond (90gal) that was very successful (proliferation
of fish, vegetation as well as looks). But alas it was in the front yard
and a neighborhood dog thought it was a better swimming hole. Since,
shooting the dog isn't politically correct in suburban America. I'm moving
the pond into the backyard (fenced in of course). The wife knows how much I
loved my pond before and has given me a fairly generous budget. GOD I love
this woman!

I'm not trying to build a lake or anything. And I was considering another
preformed liner in the 140-170 gal range...and perhaps incorporate my other
small pond liner into the mix.

What kind of filter systems ya'll recommend? Pumps? UV or not? The pond
will be in full sunlight from sunrise to sunset.