Question
Last year I had a Landscaper install a drip system in my flower beds around the perimeter of my back yard. He installed numerous spray type emmitters.  The water sprayed so hard from these that I could only have them on for one minute at a time to help prevent over watering, run off from the planter area and deep holes dug in the soil because of the force of the spray. Without going into the whole mess, I've decided not to trust him to correct the problems and I'll re-install the system myself. I've learned what little I know about sprinkler systems from the Internet,books,learn by doing and asking at the hardware store and do fairly well on the regular lawn sprinkler system stuff.  I've never done any drip system stuff though and need help.

I've dug up the drip line, which I believe to be a 1/2" poly line and tossed it. I'll start from scratch rather than plug all the holes I don't need.  The end of the poly line was connected to 3/4" PVC pipe by some kind of adapter I guess that had a filter screen at the end where it attached at the PVC side.  The PVC pipe extends approx. 12 ft to the sprinkler valve which is wired to a timer along with the other valves in my sprinkler system.  I didn't see anything at the value or where the PVC attached to the poly pipe that looked like it could be a regulator. The value is piped just like my other values and is the same type of value as is used for the lawn sprinkler heads.

Questions -
1) Where do I attach a regulator for this system? At the value end or the end of the PVC pipe before attaching the poly line?
2) Do I need a "back flow" value or is that taken care of by the anti-syphon value? If I do need one, where does that go in relation to the regulator?
3) How do I determine what type of regulator to put on? I basically just need to get water to the roots of these plants & flowers.  The lawn sprinklers kind of mist the plants/flowers when they're on but don't provide enough water to consider the planter watered from just the lawn sprinklers.  
4) Do I re-install the filter screen back where I found it or does it go somewhere else?


Any help or suggestions will be totally appreciated!!! I really am unsure of myself at this point.  Thank you


Answer
1) Install the pressure regulator near the valve.
2) The anti siphon valve is a backflow preventer, and should be sufficient unless your community requires something else.
3) Most suppliers for drip equipment sell pressure regulators that just install in the line or at the valve.
4) You should put the screen upstream from the first drip emitter, but it is best to put it near the valve for maintenance purposes.