First post. Pool had line built in to hook to sprinkler system for daily/scheduled filling. I hooked it up on a zone with other sprinklers and it filled as planned. However, the sprinkler system is designed to drain from lowest sprinkler when zone goes off which caused a siphon from pool. I tried a couple of pvc backflow valves which didn't work. It appears i need an anti-siphon valve, but all i'm finding require above ground plumbing (12" above highest sprinkler). Is there a way to solve this problem without above ground plumbing?