Is this a good swim work out.?

I'm looking for a good swimming work out to lose weight. I'm not familiar with the swimming language but I know how to swim every style. Right now I've been swimming 1500 meters in 200 meter intervals with a 30 second break and then end the workout with a 100 meter interval. The pool I swim in is 25 meters. So down and back is 50 meters. My workout consist right now of only free style swimming. Thanks