Clean, neutral smell, keeps interior of humidifier free from sludge and gloppy sediment on the bottom and sides. Works fine in my humidifier, which is on 24/7 due to my pellet stove. No lingering scent. Used to control bacteria in humidifier.

It keeps the filter and water from turning to slime. The relative inconvenience of having to measure this product into every gallon of water is well worth the effort for a mold free filter.