Pooldash

Thousands of professionals across the world already use pooldash to keep their pools blue... you should too!
This app was built for professionals, but don't worry -- beginners can use it too! Just enter whatever chemical readings you prefer using any test kit you own, and pooldash will tell you exactly what chemicals to put into your pool.
We, the creators of pooldash, don't know everything there is about water chemistry. That's why we created the "formula" system, so that people around the world can share their own custom calculators within pooldash.
By default, you can adjust the chlorine, bromine, salt, pH, total alkalinity, calcium hardness, and even the cyanuric acid levels in all of your pools. You can even configure target ranges and chemicals used to treat the pools (see screenshots).
Pool Doctor gives all results and explanations in pounds, ounces, grams, kilograms, liters, gallons, or even in the number of scoops (you can enter custom scoop sizes); and changing units is as easy as pressing a button! This app supports chlorine, salt-water, bromine, copper, and all sorts of swimming pools.
You can save your history and email it, export it, or even ignore it if you want.