If you have an tang or herbivore fish..don't worry if the caulerpa gets sometimes in the main tank. It's a fish candy. I had a drilled rubbermaid basket hooked near the waterline..my tang bashed it when i was away...no more caulerpa..i had 2 handfull. His belly was so huge.
If you check some sump/refugium on the net...you'll see that almost everytime, people use huge load of caulerpa in their sump, often with no super lighting. Cheap, efficient to eliminate nitrates/phosphates and doesn't require calcium..unlike halimeda. It's a wanted pest
that reproduce so fast.
I find a guy who sells mangrove...very cheap and they look great. I'll test it.
It looks more difficult to handle, due to the size/head out of water matters..
Mangroves are endangered by hotel chains in Florida..so why not help to save those precious plants/trees. Oh yeah..and if they are endangered..so are many fishes and creatures that look for protection behind the mangrove's roots.