Originally Posted by fall-line
If you are talking about threading on the fittings to the pump head, I suggest just adjusting the amount of teflon tape you add to the threads. This will allow you to tighten a little more or a little less. Also use a large wrench/channel lock/pipe wrench and make sure you are getting all you can out of it, you can usually tighten further than you think
Not directly on to the pump head, but on to another fitting. My inlet on the pump is pump head -> coupling -> camlock -> 90° elbow -> T -> ball valve / camlock for hose connections. Outlet is pump head -> coupling -> camlock -> 90° elbow -> ball valve -> camlock for hose connections. A picture would probably make this much clearer.
I'll give extra plumbers tape a shot, I was under the impression that using too much would cause problems with leaks so I didn't consider that.
Originally Posted by Misplaced_Canuck
Be careful how much you tighten. Polysulfone has a limited tensile strength before it will break. It's much lower than stainless fittings, for certain.
Thanks for the warning. I did a polysulfone coupling on both sides of the pump and then did camlock fittings on those so I could have less bits sticking out of the toolbox when it was being moved/stored. The coupling was recommended from Austin Homebrew (I think) to prevent damaging the pump head with the steel threads.