My Original plan was to do waterfall one as well, I was going to split it off my return pump since its a 6000l/h DC pump. I even catered for it when I did the plumbing. never kept loadshedding in mind.For nutrient export I would go with the algae scrubber. I'm going to be doing a waterfall style one hooked up to a batter backup for if the power goes off. If you can fit a large enough refugium with good enough lights that would probably be the easiest and be the least maintenance.
The other thing is also with up flow one you have to use a airpump and they are noisy so I am between rock and a hard place.