You don't need one on a reef...
Have heard mixed reviews of the idea over the years when I followed freshwater discussions a little more. Seems the theory is sound it's just hard to get it completely correct once built kind of thing.
If you're looking for a DIY project, have you thought about making your own glass? I mean ... how hard can it be. First, grab a bucket of silica sand. Then, make yourself a really, really hot fire, .......
