What is a "Skippy" filter ?

http://www.skippysstuff.com/biofiltr.htm

We also have a small pre-form which has two goldfish and some oxygenators,
and a small
(650gph) fountain pump in, and we'd like to filter that, but don't want to
go to the expense of the Hoselok system for something that small.

So could I use some other filter, eg Skippy ?

Yep...you can make a Skippy filter any size to suit your pond's needs.

I am a believer, since my pond cleared up in a week, after buildoing a
Skippy filter. Of course, that could be due in part to the bacteria
and barley straw pellets I put in the bottom of the Skippy filter.