External Pumps - Info

[gummi]

Hi,
I am thinking about going to an external pump. I've seen pictures but how do these work in terms of plumbing and water movment?

Are they loud?
How do you mount an external pump?
Leak problems??
Recommended brands?

I have limited sump spacce so if I can save space with an external pump intead of submergible, my refugium can be bigger.

 

[jeffgp]

the PS1's and the T1's are small and quiet ... that will be the next pump ill be getting for my tank .. they do have a small heat transfer but a cooling fan will fix that