I have kept a single mangrove in my reef now for the past few months.
It's not for filter purposes, instead for looks mainly.
I decided to plant mine in the substrate and it's doing really well. Over the last month two new leafs have sprouted. Despite some belief my mangrove is completly submersed, which after reading an article by J.Sprung I learned that mangroves will also survive and grow in this state.
The article is titled "Magnificent Mangroves-A Guide to the Ecology and Care of Mangroves", it's a great basic read for anyone who wishes to start using these wonderful plants. I don't know if it's from one of his books or if it's an article of some sort. maybe try his website at
www.twolittlefishies.com
I was given a copy when I picked up my mangrove a few months back.
cheers, sumpfinfishe