You can order a Hanna from j&l aquatics, decent shipping times even now.
https://www.jlaquatics.com/hanna-copper-high-range-checker.html
A bit pricey, but it works fast and accurate, I'm using one to monitor my copper levels.
From what I was told/read about lions when I was having issues is fed a good diet and kept separate from copper and infected fish/water and it should be able to recover on its own. Perhaps a freshwater dip between transferring to a different tank from the DT and QT to minimize possible reinfection? My eel, also sensitive to copper and parasite resistant is living in a 30 gallon tote with some rock and couldn't be happier.
Rock definitely absorbs copper, I left a few handfuls of sand in my tank I couldn't get out and my levels dropped 0.2ppm over a few days. What I did was get a big plastic bin, chuck the rock in with a powerhead and heater. Keep it in there for the full fallow period, 76 days for ick I believe and it should be fine to reuse.