http://forum.honeyflow.com/t/how-do-i-determine-if-i-need-a-2nd-brood-box/5258/15?u=martydallas
This post should help. I do believe in your area as well it will be suggested you have 2 brood boxes at a minimum and one honey super i.e. your flow frames. Do check with your local bee club or mentors to find out if 2 brood boxes is recommended.
2 brood boxes are recommended for couple of reasons, one being after we harvest the honey out of the flow frames there may not be enough honey left in the single brood box to support the hive over the winter. In tropical climates this is not an issue for they can forage all year long. That is why Cedar and his father only designed it with one brood box and one honey super. The other reason to brood boxes are suggested, is that one brood box may have a total of 25,000 bees, with 2 brood boxes you’re likely to have 60,000 bees, with more bees more honey is produced faster. Studies have been done to look at having 2 hives with smaller number of these or have one hive with a larger number of bees, and the one hive with a large number of bees produces more honey than the 2 smaller boxes of hives.
I only have one hive for I live in a major residential area and just a little timid right now. But is highly suggested that you always have a minimum of 2 hives just so that you can do a compare and contrast against the 2 hives. You can tell if one is doing something different than the other and you can properly adjust. Again I only have one but I have a mentor that I go out to his farm quite often and help so that I got a little bit of compare and contrast.
I hope this helps, me being a new beekeeper like yourself would suggest maybe read more of my questions it may help you find answers.