It is important to test your aquarium weekly to verify good water quality with RapiFast® Aquarium test strips, 6 in 1 strips with colorful comparison chart, suitable for both freshwater and saltwater fish tank. - RapiFast® test strips, combined 6 most critical water quality standard parameter,Hardness, Nitrate, Nitrite, Chlorine, Carbonate, pH. - Immerse the strip for 2 seconds and then remove the strip, do not shake excess water off, and then put the strip horizontally for 60 seconds, compare against the color chart and read immediately within 30 seconds to get accurate results. - Can be used for testing various water quality: all fish tanks, shrimp tanks, aquarium plants tanks, fish ponds and many more.