Was wondering if anyone could tell me the best possible filtration system I could use for my 65 gallon tank. At the moment I have goldfish and minnows in it. I have a underwater Fluval filter, its seems to be ok, but I was hoping there was some way around changing the tank water every week? which isn't too bad, because i use the water on my pot plants. I am looking at getting another tank, and want to get the best filters possible from the get go. There is so many available on the market, it is getting confusing :(

There are tons of filters out there and many are fine. I can only suggest the one's I've used and liked (or not). I use and prefer the Emperor 400 filter. I now have one on my 65 gallon tank and one on my 50 gallon tank. I do weekly water changes though. It's good if you change some water each week as most people don't.

thank you Robyn. I got the new tank. Do i now decide on the filter, or does it depend on what kind of fish i keep as to what I should use?

It depends a little bit on the fish. For example, if you are getting fish that like low water movement, then the Emperor would be too much for them. If you're getting messy big fish, then you need a good filter.