"Cycling" in a pressure system is generally when the pump is turning on and off too quickly. Pressure systems are specifically designed so that the pump runs up to its maximum pressure, then you use water from the pressure tank, until it reaches the minimum pressure, at which point the pump turns back on and runs until it reaches the maximum.
The recommended minimum run-time for a 1-2HP pump is usually 2 minutes. How you get to that is based on the flow rate of the pump, and the size of the tank.
Based on your 150gallon tank, and not knowing your flow (in gallons per minute, GPM), based on this tool here's some example flows/times:
- 16GPM: 3 minutes
- 20GPM: 2.5 minutes
- 24GPM: 2 minutes
As you can see, the higher the flow rate, the shorter the pump will run.
In your case, it sounds like one zone is basically matching the flow rate of the pump (you could verify this by watching the pressure gauge while it's running, it should be fairly steady). While this may reduce pump starts, if you use water elsewhere at the same time, your pressure will drop and the pump will not be able to keep the pressure as high.
Now, the flow rate the pump puts out depends on a couple things, most importantly: the pump itself (and now many stages it has), and the depth to the water level. Each submersible pump will have a chart showing the flow rates at different depths, so you'll need to find your model and the water level to figure this out. Here's an example though, using a 2HP pump I found while running at 60psi (depth to water: flow rate):
- 20ft: 23.9 GPM
- 60ft: 22.7 GPM
- 100ft: 21.3 GPM
At first glance, this seems fine. My guess right now is that your first zone matches the flow rate of the pump, while the second zone is simply a lower flow rate than the pump. It's no problem, things are designed to work this way.
If you really want to reduce the cycling, you can hook up a bigger or a second pressure tank. This will give you more capacity, and so the pump will run longer, but it will also stay off longer while you use water stored in the tanks.
Now, if you had fast cycling (eg, <2 minutes run time) or "rapid cycling" (a couple seconds of runtime), then that would indicate a problem with the pressure tank. Normally the tank should be pre-pressurized at 2psi below your cut-off (low) pressure point - so in your case 43psi. To check this, you'll have to turn off your pump and let the water drain out (open a tap somewhere). You can top it up with a normal air compressor.
Some additional things to consider:
1) You could put a flow detector in the water line that feeds to the input side of the sprinkler valves. This way you could detect when one of the sprinkler valve has failed to work according to plan. I.E. if you detect flow when you expect the valve to be off that means there is a problem.
2) You could add timer / calendar features to your microcontroller so that you can setup a watering schedule. It could very well be that some of your sprinkler zones do not need watering every day. Secondly many times in summer certain localities may impose watering restrictions to certain week days or odd/even schedule according to house number. You would want your controller to be able to comprehend that.
3) A water controller can often be extended to assist in automating the process of keeping a bird bath, fountain or swimming pool properly filled to account for evaporation. Adding some level switch inputs to the microcontroller hardware can make it easy to regulate when the water fill operation should be started and completed. Such filling and monitoring can still be applied to a schedule as in 2) above.
4) You could add in circuitry to detect the current flow going to the sprinkler valves. Detecting no current when you've turned on the valve can indicate that the wires to the valve have become disconnected or broken. Detecting excessive current can indicate that the wiring has been damaged and the conductors going to the valve have become shorted together.
5) Many times home owners will have landscape accent lighting or sidewalk/driveway perimeter lighting. A controller of the type that you are proposing can easily be extended to provide automated turn on/off for such lighting according to a schedule.
6) And if you go so far as to implement lighting control you can extend that to schedule the on/off cycling of other seasonal lighting such as outside Christmas lights.
Best Answer
Yes, it's a fine idea to add another valve and manifold location and to convert that long section of red so that it's an always-on main line rather than just a zone 2 feeder.
Your desire to add a separate zone for the garden, rather than make the lawn zone water the garden too, is a good one for several reasons. For example, gardens and turf grass have different watering requirements; and broadcast watering over the garden wastes water and supports growth of weeds all over the garden.
When running wire to the new valve location remember that you need a conductor for every valve, plus one as a common, plus one or two spares for when "it would be nice if..." happens later. ;-)