Accelerated Hydrogen Peroxide Indicator Strips
C$29.95
Using CS20? The solution you are using will lose efficacy over time as it is exposed to air and even minute amounts of water from your cleansed implements. Be sure to do your due diligence and check your solution each day before using. 
Accelerated Hydrogen Peroxide Indicator strips will give you a pass (your solution is 6.3% > and still effective) or a fail.
50 test strips per bottle