I've owned 2 AC
filters, Both of them I have to reprime all the fricken time because they somehow loose their syphon, even tho the intake, impeller, impeller seat, and everything are clean as can be.
You ahve to be careful when putting filter media in them because if you push it down to fast it'll overflow all over the place
and one, after just over a year of use, has gotten so slow that it barely trickles water out, and its rated for 100GPH, it dosn't even pump 1GPH.
On the other hand, I've never had ANY problem other than operator error with any of my Penguins , I run penguins on ALL my tanks save for 2, one that has the trickling AC
thats going to get replaced ASAP
, and my 10gal Danio/Banjo tank has a whisper filter for a 40gal tank on it. ]