Hi guys, I need some help with filtration

Some time ago i update my filter from a Top Fin canister to a Penguin
(marineland) with a bio wheel. Now i am thinking to add a second filter and
I d like to know what is my best option.

I have a 30G tank
1 Mesonauta Festivum
2 Blue Rams
5 Neon
5 Rasbora Harlekin
5 Rummy Nose
3 Hatched

Thanks

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Paulo