I'm using the NilocG aquatics Thrive invert-safe all-in-onefertilizer for my plants and they're doing great. I have neocaridinas and nerites in there and they're fine. It does have both nitrogen and iron, and has no copper. I think you could also do dry ferts? I know there's a lot of information online about that (and you can target specific nutrients) but I haven't done that at all myself.
All are safe, including ones that have copper. We humans have iron-containing blood, hemoglobin, and inverts have copper-containing blood, hemocyanin. Trace amounts are no issue
Nilocg's Thrive line is likely the best all-in-one. ThriveS contains no copper but is more dilute than regular Thrive so it's less economical. The most economical for a large tank such as yours would probably be dry fertilizer, which Nilocg also sells