Biologically healthy 29g tank with 6 columbian, 3 red eyes, 6 black neons and 4 cardinals Tetras. I bought a back-up filter eheim 2041 on sale and wonder which one I should use for maximum performance...see, I kind of care for the fishes I have and they gladly went thru the cycle phase with great pride. I have a subtle impression that the Tetrefin filter has lost some of its original flow (changed filters twice with a 7 days soaking time ).
Thanks
Jean
Thanks
Jean