Upgrade 16 IN 1 TestsCan simultaneously test 16 kinds of total alkalinity, pH, hardness, cyanuric acid, total chlorine, free chlorine, free bromine, nitrate, nitrite, iron, chromium/chromium (VI), fluoride, copper, mercury, fluoride, carbonate. More effective than other spa test strips. At Home Test StripsThe spa hot tub water test strips set have instant and reliable results, simple and clear instructions. Just dip and compare to the big color chart on the bottle. The desired range is marked on the bottle. 30S Fast & AccurateImmerse the pool test strip in water for 2 seconds and let it keep in the air for about 30 seconds, then match the color of the test strip to the back of the bottle to get a reading. it only takes 30 seconds. Pool test strips are easy to use even for beginners High-Percision ResultsDesigned for warm water, these water hardness test strips easily to provide instant and reliable results without much effort. Come with an excellent color card to explain the test results meaning, also tell you which aspects you should take care of about your pool. Pool & Spa EssentialsHot tub test strips suitable for drinking water, aquariums, swimming pools and spas, sewage and other liquids. Using Test strips, you can make sure you keep the right amount of chemicals in your pool to avoid health problems and equipment damage. [Storage conditions and shelf life] : Storage conditions: 2 ~ 30 in a dry place away from light (2 ~ 8). Product shelf life: 2 ~ 30 store in dry place away from light, shelf life is 12 months. Shelf life: After opening the bottle, the lid should be sealed and stored in a dry place between 2 and 30 away from light. Please use it as soon as possible.