I'm fairly certain that that would indeed be too much. However, the motors for AquaClear filters are all the same--save for the AC110 which has a different design--which means the impellers are interchangeable. I ran an AC70 on a 20 high with an AC30 impeller because the standard impeller was producing a large crater in my substrate and uprooting my plants, even on the lowest setting. So you could run an AC50 and take advantage of the large media capacity while using an AC20 or AC30 impeller to prevent monsoon currents.