Any plant will grow more quickly if it is "grazed." Think about the grass in your lawn. It grows faster when its mowed than if not mowed. By thinning out the macroalgae you are keeping it in a growth stage, rather than in a mature stage. Phosphate, and other nutrients, will be utilized much more readily by rapidly growing macro.

By simply removing the macro from the tank it is truly exported. If you feed it back to your herbivores in the main tank it will be recycled. Some percentage is absorbed by the herbivores through growth but much will be excreted back to the water. IMO, the organic phosphate in herbivore waste is much more likely to be skimmed than inorganic phosphate.

I'd like to hear what some of you think on this topic.

Gary