I suppose it depends on what you have in the tank at the moment. If you want the flow to reach further across your tank then the 4's are the way to go. I've got two Koralia 3's in my tank (80g) and really I would of preferred to go for some 4's instead.
I would go for the nano for your 12g. They are small and if you need more flow then get another one.
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80gal with live rock (35kg/70lbs), 30gal sump, refugium with live rock, chaeto and DSB, Bullet-1 skimmer, Fluidized Reactor, T5 lighting (6 tubes), 4 x Koralia 3's. |