Help Need to pick chlorine / acid dosing system

I am trying to install a chlorine / acid dosing system in my parents
pool. I want to give them two options one with a ORP and pH meter and
one which is just manual. They use liquid chlorine (12%).

I am looking to find some guidelines and formulas on how to pick a
dosing pump. Anyone have an online link or a guideline for calculating
pump specs. What do I need to look at... I have been surfing the net
for 3 days and have come up empty handed.

Any help would be appreciated.

Thanks,

Doruk