This is the filter I have in Leroy's 22 litre (almost 6 gallons) tank.....
From the filter baffle sticky, I'm going to use the water bottle idea and hope it fits. :)
The filter isn't too strong, although there's a little bit of a current in the tank, and I'd like to make more of the tank free of a current. Last night he was sleeping in his little ceramic dog house (very cute) I think to get out of the water flow. So, thinking the water flow in the tank is more than he likes.