Just because Eric is so fond of the Caulerpa algae:
Nitrogen- versus phosphorous-limited growth and sources of nutrients for coral reef macroalgae. S.T. Larned, Marine Biology (1998) 132: 409-421
C. racemosa had a dry weight N:P composition of 150:1. C. sertularioides, 200:1 (Table 2). WOW!! Some plants (Codium, Sargassum, and others) grew better in an elevated P environment. Both Caulerpas showed retarded growth in an elevated P environment, and elevated P slowed their growth more than any of the other studied plants (Fig 2).
It doesn't look to me that Caulerpa is the best choice of plant for export if getting rid of P and promoting reasonable N:P ratios in the tank water is the goal. I'd further speculate that using Caulerpa as a main source of export could set up conditions where P becomes excessive, limiting the Caulerpa, and causing N-fixing Cyanobacters to kick into full throttle.
Anybody have any thoughts?