External or submersible?
Ihave used submersible Quiet One and Mag Drive pumps with great success. Although the magdrive seemed to increase the water temp a tad.
I will soon have my first external pump going and will then be able to offer advise on them. With that said, I have read that external pumps can be more energy effecient and add less heat to the water than the submersible pumps. I purchased an Iwaki 55rtl external pump for my new tank.
Good luck with your decision and I am glad you could use the sump
