Algae certainly sucks up a lot of trace elements that could otherwise benefit corals. There have been plenty of dry weight tests that show what algae consume. There are also plenty of people that have to dose iron, nitrates, ect to keep their algae filters going.
Triton in this respect is self-fulfilling in that you may show some depletion rates per their tests as the algae is sucking up essential elements. With no water changes, the setup dictates you having to buy and dose elements....just send them another $50 and they'll tell you what to do. They've essentially taken a standard nutrient tool and turned it into a money making "method"
I don't use algae filters as I don't want competition for my acropora systems and there are many other options that don't directly compete with the corals for trace elements and nutrients.