A 14L tank would be too small for a hang on back filter with a betta. I have a HOB for my 10 gallon (37.8L) and my betta likes to go into the flow every now and then almost as a game (they are incredibly smart fish). I agree a sponge filter would be best in a tank of that size or less so, but still good, an in tank filter with an adjustable flow like i have in my 2.5 gallon (9.4L) its rated for up to 10 gallons. Heavy planting would cut down flow though for any size filter and bettas love to hideHi everyone! Would I be able to put a Betta in a 14L tank with a 180L/PH (it’s an aqua one clear view 100 hang on filter)? Don’t want the current to be too strong for him [emoji4]