i have never heard of anything like that, but anything is possible. the fact is that other algae lives, just not chaeto. i did add the 175 watt halide but have been so busy i haven't gotten around to adding new macroalgae as of yet.
david, i might have looked at the flow, except for the fact that initially i grew chaeto in the exact refugium for over a year with no trouble. i have also kept chaeto in "non- tumbling" situations multiple times and have found it thriving also. i find the "tumbling" popular advice to be less than 100% accurate.