Mineral sticks have been around for years and many hot tub owners prefer the simplicity of dropping in a stick into the filter area and knowing the spa water is being sanitized. The official line is that mineral sticks do not replace bromine or chlorine, but allow you to use less of those sanitizers in combination with the mineral stick.
Nature2 is a brand name mineral stick that has received praise in the press. Comments and testimonials range from those that say they are using just a teaspoon of chlorine to activate the minerals, to those that say it is not compatible with a bromine based system.
The mineral sticks are clean and odourless. They seem to last about 3-4 months before needing to replace the stick with a new one. If you buy the Nature2 mineral stick online, you can buy 3 or 4 and get a one year supply with one order at a discount. Nature2 Spa Stick Mineral Sanitizer for Portable Spas
The yellow stick is usually placed inside the filter compartment per directions on the package.
The Nature2 mineral cartridge sanitizer is EPA approved and works with the existing filtration system in a spa for hot tubs up to 500 gallons. The claim is clean, clear water without harsh chemical side effects.
Zodiac is a brand of mineral stick that reduces the amount of chemicals needed, reduces the odour associated with those chemicals and is easy to install. The mineral technology helps destroy the bacteria on contact. It also reduces potential eye discomfort or skin irritation and works great with a little chlorine. The only downside is that they need to be replaced every 3-4 months, so plan ahead and get 3 or 4 at a time.