I have a small chlorine feeder, but my pool is indoor, so it runs about 2.5 hours at night to rise FC to 2.5-3 from 1-1.5. With an outdoor pool the chlorine pump should be able to keep up with the demand during the day. I remember when I took care of an outdoor pool couple years back, there was an automatic chlorine and acid feeder. The system was fully automatic and it was keeping both PH and FC in good levels. BUT, when the bather load increased and the weather was very hot, I had to shock the pool often and add stabilizer. After the management decided to turn over the pool care to Lifeguards on duty, in less then a week they created a green swamp, tenants called health inspector and she shut down the pool. It took those uneducated teen lifeguards (i assume they trusted the computer to do the work for them) about a week to get it back to normal.
So, in my opinion - chlorine feeder is a nice thing to have, but you still need to test it every day and add more chemicals as you need - manually! Also, try purchase the pump that is rated for bigger pool then yours. Maybe it will be enough to keep up with higher then usual demand.