Hello! Pretty new to the hobby and learning every day! We have a 32 gallon Brute trash can that stores the prepared RO/DI saltwater and copper concoction for our quarantine tanks. I started noticing a strong stagnant water smell coming from it. The plain RO/DI water smells fine. Also, all 3 of my quarantine tanks now have purple slimy stuff (cyano?) on the top rubber portion of the heater (and why is it only on there in all 3 tanks??). I was treating them with nitrofurazone, but not anymore. I’m due to do a water change, but worried this water is full of bacteria. The trash can is about half full…do I dump it, sanitize, and refill OR is it safe to use it? Also, am I supposed to have some flow in the trash can? Could it be because I put a heater in there to warm up the water? Thanks for your help!