It is an idea and one that I hear often. I'm not going to say it CAN'T be done. But you'd certainly reduce the "quality of life" and possibly the life span of the fish.

Now.. with that said, if you had the RIGHT system set up, you could do this. If you, for instance, had a "temperate" tank; housing species of the North/Central Atlantic, and the temperatures were kept in the 60's and 70's and THEN you had an attached fuge...you could keep H. Erectus in there. You'd still have the problem of "refugia" in that the refugium is no longer a refugium for pods, etc. but a refugium for the seahorses, but it could be done.

Here's a good podcast to listen to... If I may say so myself

http://www.talkingreef.com/forums/showthread.php?t=404

Dave