You asked me about how to keep maintenance simple, but yet your parameters are stable and you're buying additional supplements to add daily/every few days...
I would simplify by just keeping flow up, keep the skimmer going (they're easy to clean), and do your water changes every other week. I don't like floss, carbon, or GFO unless they're needed. I know I'm too lazy to be changing floss out every few days, and the only dosing I do by hand is coral and fish food, which can be skipped here and there without issue.
Your setup looks really nice so far. As it matures, you can always switch up your maintenance routine, but you can't get easy maintenance in the beginning, or you'll just be having algae headaches all the time.
The bright side of losing the sixline is that they're often aggressive. I love sixline wrasse looks, but they just tend to be too aggressive to keep in anything but very large tanks, even though they're quite small. It totally depends on the individual (same with most other species that people want to keep in their reefs), but in the case of a sixline in a nano, you have to be especially cautious.
Hope that helps, feel free to ask other questions, and I'll check back on your thread.