IMhhhhO It's only a 29 so I'd to a full tank tear down. Pull the sand, replace it. Get some more quality rock and re-aquascape. Before I did that, I'd frag off any corals you wanted to keep onto plugs or rock rubble so I could rearrange what I had.
How low is low light? What's the fixture? Some colorful low light corals off the top of my head: Euphillias, acans (somewhat low anyway, put them higher in the tank), mushrooms, fiji leathers.