There are pumps that inject sodium hypo. into your pool, these normally are connected to an electronic device that reads your Cl - pH levels constantly and adjusts as needed.
They're expensive as you might guess, and in my experience aren't totally reliable. Our locations pumps run 24 - 7 and more than once we have showed up for work in the AM and found half of a 50 gallon drum of Sodium Hypo pumped into the pool. That's no fun