Here's a good description of
ogo
(scroll down)
"Gracilaria (ogo) is also one of the very best algae for vegetable filters. It does require brighter light than alternative genera (2 watts per liter approximately) and appreciates very strong water movement like Chaetomorpha to keep the colony tumbling for good health and growth. With these provisions, though, it has the added benefits of great aesthetic beauty and it is quite useful for feeding herbivorous creatures. Picture and Caption by Anthony Calfo
Gracilaria can be equally effective as Chaetomorpha for nutrient export and has the added benefit of being more palatable to herbivorous fishes if (re-)cycling of the nutrients is preferred instead. In fact, the genus has been quite palatable to numerous creatures for centuries as humans can testify; it has been eaten by coastal peoples for many years and is known as the culinary delight "Ogo" to diners of Asian cuisine (it is a popularly recognized ingredient to cosmopolitan sushi diners that enjoy "seaweed salad" with their meals!). Gracilaria is a organism of great fisheries interest which generates millions of dollars in revenue in Japan and Hawaii for example. Commercial organizations culture the algae on lines or tumbling in baskets in shallow, coastal tropical waters. As a refugiums species, it has all of the same befits as Chaetomorpha (namely, multicellular and stable when pruned, fast-growing and non-toxic). It is somewhat more demanding about receiving strong water flow and really excels if kept tumbling, although Gracilaria will attach to a substrate readily. This "Ogo" is also more demanding about lighting; I recommend something close to 2 watts per liter of water in shallow refugiums (tanks less than 40 cm deep). Because of the greater demand for lighting, a tumbling colony of Gracilaria can be kept more efficiently under lower lighting, you see now.
Tip
When red Gracilaria is getting good, bright light, it will often turn orange or even slightly yellow, particularly at the fringing ends. Many aquarists associate this with poor health, but the opposite is true! We only think the color is sickly because most of us like the solid red color better. In fact, a darkening (to deep blood colored red) is actually a sign of lower light conditions and not really conducive to optimal performance in a "vegetable filter" refugiums.
In summary, there really is no one "best" species of algae at large. Rather, we must each evaluate the needs and benefits of each candidate to suit our own preferences and needs in aquarium husbandry. All three genera mentioned here can be used effectively for nutrient export. For the busy aquarist that needs minimal complications, Chaetomorpha is clearly the best algae. For enthusiasts keeping heavy populations of herbivorous fishes like Tangs/Surgeonfishes, Rabbits/Foxfaces and Angelfishes; the delightfully edible Gracilaria is the way to go. And for disciplined aquarists that are up to the challenge, the aesthetic beauty of more than forty species of decorative Caulerpa awaits them. A different flavor for every taste preference!" (emphasis added)