I agree with bigger is easier to keep your tank parameters stable if u run into a bad episode...but I have a nano evo 13.5 and have had no issues... I had a 55g years ago and had trouble keeping up with larger water changes. With the nano I do a 3 to 5 gal water change per week and find it easier to keep. I've had no issues with the nano and find the small water changes easier to keep up with. Of coarse this all depends on your bio load. I have 2 clowns 2 shrimp (cleaner and peppermint) 3 nassarius, 2 scarlet hermits, 3 blue leg hermits and 3 trochus..... 6 zoas, pulsing xenia, hammer, a candy and gsp..... all is running smoothly with no issues. Hope this helps, good luck going forward!