There are many types of macro algae that can be used. Here are some description that I picked up from other sites. Note that these are not my descriptions and grape Caulerpa can cause problems:
Red Gracilaria
Tang Heaven. Beautiful red color. This algae almost looks like a root system. Quick refugium filler. Best floating. It is a very "rubbery" algae which divides through fragmentation. It is heavily regarded as it is a very highly nutritious fish food which many marine fish will readily consume. Grows well in both temperate and tropical waters. This Red Macro Algae is known to combat, prevent and cure head and lateral line erosion disease.
Chaetamorpha
Brillo Pad Algae. Spaghetti Algae. Easy to control. Will not attach. Very easy to trim without any possible injury. Great breeding ground for detrivores.
Green Grape Caulerpa (Caulerpa Racemosa):
This algae is looks like it has mini little grapes growing on it. It is very easy to control because it grows in clumps. Very nice looking. Good floating, or anchored, will attach readily.
Prolifera
(Undulated Caulerpa)
Undulated means to look wave like, which is a perfect discription for the scalloped edged leaves of this algae. Can be planted in sand, left floating or attached. Will grow into a big beautiful lush bed in your substrate.
Ulva
"Sea Lettuce". Thin bright green leaf-like appearance. Great aid in the proliferation of amphipods.
Mermaid's Wine Glass(Acetabularia Sp.)
Also called Champagne algae or Tea cup algae. This algae slightly resembles the green grape algae, and is therefore mistakenly sold as it, especially on Ebay. Seeing them together, you can very easily see the difference.It is also easy to control because it grows in clumps. Grows easily and quickly. With this algae, each "stem" and "tea cup" is actually one single very large cell. Very neat looking and extremely bright green under any decent lighting. Good floating, or anchored, will attach readily.
