I agree with Krish about hiding the "ugly" in the sump/refugium. That's the proper way to use a Macro Algae as a nutrient exporter anyway. Other macros that are more pleasing to the eye have the drawbacks of being more aggressive, requiring supplementation (as with Halimedia needing Calcium) and having the ability to tenaciously attach themselves to anything and everything, including your corals!!
On the other hand, the "planted SW tank look" can be very nice. I have Halimedia growing in my 75. I recently removed most of it from my 46. I have to regularly "weed" it out though. I do dose Calcium, Alk and Mg for my corals and clams. Without dosing, Halimedia will quickly consume these elements, which are needed for coral health and growth. I've also got some Feather Caelurpa growing in a 10 gallon Pod tank that I'd love to have in my 75, but my Yellow Tang likes it too much. There's also Eel Grass, which is a true plant, not an algae as it has a root system. It's somewhat hard to find though. I don't know a lot about it's care, even though I also have some of it growing in my 10 gallon. Once I get a large enough spread of it in the 10, I may try planting some of it in my 46.
