This is a new product that I just installed. It does not reduce the flow, but it does adjust the minutes on the irrigation schedule. You set it based on July 31 minutes on the schedule (Worst case scenario), and it adjust for temperature. It also uses rain sensor, temperature gauge, freeze gauge, and ET data based on past temperatures for your region. It is fairly inexpensive retail 100ish. It will only work with the hunter Pro-C, and ICC, or better.
Check it out.
I have installed only 1, and I am curious to see the result.
Dan