I DIY'd mine for about a quarter the price of the Spectrapure unit. Then I spent another quarter of the price fixing my DIY. Then lost about three times the price of the Spectrapure unit in corals and fish when my DIY failed. Just warning you now...
Spectrapure has some decent sales. There are others as well, but a fully engineered, working solution from the start is often the cheap way to go in reefing. Wish I'd learn that someday...
Jeff