Suggestions for new Aquarium

[sunny21]

I have a 2 feet by 1 feet fresh water aquarium containing 2 red cap orandas and 1 shubunkin gold fishes. I have under gravel filter. Do i need any other filters? What aquarium testing kits do i require? Please suggest!

[Spidyman]

As a member here im going to tell you that you are overstock. goldfish are messy animals so 3 in a 2x1 tank(20 gallons right?) is not going to work out well. You are looking at more like 1. (I'm not a goldfish person but i do know a little about them.)
As for you question i would recommend that for a 20 gallon goldfish tank you are looking at a filter rated for around 40-80 gallons. I would say go with an aquaclear 70.
As for water testing most people own API's master test kit. It gets the job done and is far more accuate then any strip. There are some better liquid test kits but i forgot what they were since I use API and that is all any store around here carries.