I tried to respond earlier but then class's stated and when I went to continue after class everything I had written was gone so here's my second attempt

First off I find that macro algae in a refugium as a method of nutrient export to be one of the simplest and by f far the most cost effective way to maintain a reef environment. It requires less work than a reactor would and can be very effective if you allow the macro to grow quite large before exporting. The only reason I do not have macro growing in my sump is because my system doesn't have enough nutrients to support them. This is likely due to my reactors, i was take into them earlier when I was less familiar with the hobby.

If I was to ever take my reactors offline, i would for sure grow macros is my sump. I do not find them to be poo factories at all, and if you could expand on why you think they are it would be appreciated. Nothing is more simple that allowing something to uptake excess nutrients and then remove it from the system, especially when that something is grown.

Although I would not use chaeto, i would likely use caulerpa racemosa as it is very edible for herbivores such as tangs and rabbit fish. This way it become nutrient recycling and is a cheap and healthy way for your herbivores to relieve the right diet.