I have run an in-sump pump since i setup my reef tank in jan 2002. Last weekend, I switched to an external pump. The temperature of my tank decreased from 80 to 75 degrees. This will make an enourmous impact in the summer, when I have a huge problem keeping the tank under 83 degrees. After this conversion, I am now a big proponent of external pumps.
Are there leaks, yes, of course, because you are drilling holes in your
sump. I sealed those holes properly. your holes in your
sump should use bulkheads, this will dramatically decrease any chance of leaks in the future.
As far as head loss, I have a Panworld 55HDX and it has a max head of 11 feet or something like that, which is pretty impressive.
Just my 2 cents.
