pH strips, seriously they are great!

Like 5 bucks and laboratory grade. Easy to read and a book will last years

Increments of.5

Litmus pH Test Strips, Universal Application (pH 4.5-8.0), 300 Strips | for Urine, Saliva, Body, Alkaline Diet, Water, Pools, Soil, Hydroponics, Aquariums, etc. https://www.amazon.com/dp/B09KKQVKYV/ref=cm_sw_r_apan_glt_i_HTNXYSC5EX2BP5EE6J8B?_encoding=UTF8&psc=1