Question
I have a half barrel pond with one 6 inch goldfish and two smaller goldfish. The pond is 25 gallons what is a good pump and filter for it?

Answer
There's not much room in there for a full filter.  There are many small pumps available.  An aquarium filter may work if it can be protected from weather.  

This is the smallest filter I could find on the web site where I buy most supplies.  It will take up a good amount of room but is not too strong for your pond.  It says it does up to 400 gallons but there's no way.  I have a 700 gph pump on my 153 gallon pond.  This is a 190 gph pump.  That's about the strength of my 20 gallon aquarium.

http://www.thatpetplace.com/Products/KW/W26A%40/Class/Pond+Filters+Submersible/T...

Otherwise, you may have to just have a small pump since there's little room for a filter.  Good luck!

Robyn
fishpondinfo.com