I bought a cheap canister filter few years back, it was running fine on my 4ft planted tank. At first it does leak a bit but then it stop and running perfectly after that, been serving me for years. Recently the 4ft tank has been tear down and that filter has been used on a 2ft tank. Due to it was designed for 4ft tank, I had reduce the outflow to half of it, it was running fine for few months and then suddenly it start to give leaking problem, put some silicone oil on the o-ring, served me another month and it just kept on leaking. Bought myself a Eheim 2213 for the 2ft tank, put this filter to one of my 4ft gold fish tank, switched back the outflow to normal and no more leaking. I guess sometimes you might to check if the pressure is acceptable by the tank itself or not too.