Does your hot tub have a mineral sanitizer? They're super affordable and easy to use and they help lower your need for chlorine or bromine. Mineral sanitizers use things like silver and copper to kill bacteria and algae and that means your chlorine levels only need to be at 0.5 parts per million and your bromine levels at one part per million. You also only have to change out your Mineral Cartridge every few months. However, since copper is one of the active ingredients, mineral systems can cause surface stains or green water, especially if you have Metals in your water.

You can use a metal sequestrant to help prevent Copper from settling on the surfaces, but it can also make your mineral sanitizer less effective.