Bests & Worsts Reviews from Amazon

Not all pool shocks are made the same. The primary active ingredient i most pool shocks (like the ones they sell on Amazon) are made with "tri-chlor", which is a blend of chlorine (calcium hypochlorite) and cyanuric acid (something that protects the chlorine from the damaging effects of the sun, but also weakens the chlorine and its availability in the pool). Too much cyanuric acid means that your chlorine is less effective, especially as it builds up. This is why pool shocks with an active ingredient of pure calcium hypochlorite (like this one) are the ones that I prefer, as they generate more available chlorine, and do not add to your pool's cyanuric acid levels.