Filteration for larger tanks?

[Cory]

In my experience sumps are great for bigger fish. But for tetras etc. I find a lot of them in my sumps

 

[reniculous1]

There is a fluval fx6 on craigslist right now for 200$

https://seattle.craigslist.org/oly/for/5287033667.html

 

[reniculous1]

I use a fluval fx5 on my 210 tall and it works great.

 

[Ripley71]

I'm trying to think what to use as well for my 120. Mine is not drilled for a sump. Is it possible to make one & just have a stronger pump to push water back up & around the side of the tank or does that defeat the purpose?