Arm & Hammer Clear Balance Pool Maintenance Tablets, 16 Count, 7 lbs $19.97 Fs Prime Amazon

http://www.amazon.com/Arm-Hammer-Bal.../dp/B005N7FI8E

Rated 4.2 out of 5 stars from 90 reviews

Improve water clarity
Maintain pH and alkalinity
Optimize chlorine performance
Convenient and no measuring