I'm using the two stems, I have a third but use it to brace the unit against the back of the tank. LOL
The only thing I did get in the stems was gunk from my live rock when I put the sand in. Theres some caught between the two where they connect.
And yes, unless you know your LFS
real well take what they say with a grain of salt. Mine kept insisting I buy damsels to cycle with. And he told me to put 2 aqua clear 110's on my 29 gallon!! can u imagine? So check here first with your questions and then make your informed decision.
Are you going salt or fresh?