If there's one thing I know nothing about, it electronics, lol. But I'm assuming for the USB fan you'd just get one of these to make it longer so it could reach a wall socket
And then just plug it into one of these. If you've got an iPhone or most smartphones really you've probably got one laying around.
This one has 2 ports so you could even plug two into it at once and only use up one wall socket.
I just use a regular old fan though if you don't wanna do all that. How much it will cool depends a lot on how humid the room is. Less humidity means more cooling effect. Back when I had only one small tank in the living room a single fan cooled my tank by almost 10 whole degrees, but since moving my tanks into my room and upgrading to much larger tanks my room is super humid and fans only cool it down by a couple degrees now.
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