I installed this auto-siphon on a small pond last summer. It has worked perfectly until recently. The water went over the spillway and the siphon was not working. Water was flowing through the pipes but the siphon never kicked in. The air inlet valves we not plugged. Any ideas?

[img]https://photos.google.com/photo/AF1QipMcF_tAqMzpZ0dRa83Vgngv0ja4QNwXJWG4YloD[/img]