hawk,

Is this going to be a DIY project? Because with a larger project of this sort(high $$$ risk) it would be better to hire a irrigation contractor to design and install the system. Otherwise you will be going through a learning curve that you may not want to pay and will only cause frustration. The advice here is not guaranteed or warranted, a contractor's is. We can help you with ensuring you get a good deal. First step get three different contractor quotes or more. These contractors will be familiar with your local environment and regulations which is more important than you think.

If you want to continue trying to design and install. First question is what do you want for your pressure and flow rate? This come from what type of plantings you are planning, what type of soil is in the planting areas and what is your monthly rainfall average for the growing season. Check info from your local state's ag extension service. If you are close to a college, check their ag info. For example how much water do certain food plants use per week, planting spacing, etc. Good Luck Aloha