My QT is an old biocube 14. It actually holds right at 10 gallons set up as a QT. I do an 8 gallon change then immediately start PraziPro and haven’t had any issues with the copper left in the 20% that wasn’t changed. Others would suggest running carbon or cuprisorb after the water change to get more of it out but I haven’t seen issues after my 80% water change.Sounds like a great idea. Thank you. When you say large water change, like 50%?
I also use a sphere of MarinPur along with the plastic bioballs that came with the tank and have no ammonia issues. I only change water to remove medications.