Eheim pumps can be used either under water or inline. I like to run them inline so it doesn't add heat to the water. There are a couple of pics on my site of Eheim 1048's runing in line in 2 different systems. You will just have to make a trip to the hardware store to get adapters and 3/8 barbed fittings.
See the little home icon under my name? That is my website.
If you don't like Dangerden (I think they are abouyt the best) try Swiftech. You can't go wrong with either of these. I own products by both companies and have no complaints. You will also see a case set up with Swiftech stuff on my site to.