I went thru many hang off the side and then under the tank filters for small 35 gallon tank
Over the tank really did not keep the water too clear and the filters had to be changed often.
Went to the under tank filters, specifically Fuval. A pain to prime and the primer breaks easily. Went thru a few and was close to giving up on fish tanks but then......
I saw the Fuval Fx4 self priming filter and got one.
I had to fiddle with the length of the intake and outtake hose connections. I trimmed it a little each time until I got the right length where the water flowed without stopping/surging.
With the stopping/surge Fuval said the Fx4 was too big for the tank. As mentioned above, my trimming the hoses solved the problem in spite of what Fuval said
The water is absolutely clear, pump is very silent.
It is a big device to do the change of filters but the filters and media really do the job!
Water testing shows no issues with my water, which comes from our well, not city water.