I am a retired American living in Cancun, Mexico where I built this pool which was finished late last June. ('08)
About a week ago the piping immediately coming out of my pump blew out! The PB's plumber had not screwed the connection all the way down into the pump housing and therefore after about 9 months it wiggled it's way free of the housing and erupted in a torrent of water washing down the walls and ceiling of my pump house. I think he backed it out to align the centerlines of the piping going into the main control valve. I rebuilt the piping (pvc) to make sure it was done correctly this time (read....no leaks or loose ftgs). When starting the system after the repairs I began to get air bubbles pulsing out of the return jets. This doesn't happen immediately. They start appear 30 min. after starting the system. I cannot find any above ground leaks, I disassembled the control valve and it appears to be in good order. The "O" rings in it as well as the clear cover on the pump are in good shape. This pool is less than one year old and is well maintained. I have no loss of pool water. I have two skimmers, two bottom drains, and two vacuum ports. The pool has 8 return jets that are evenly spaced from about 5 o'clock thru 1 o'clock. It doesn't matter which mode I have the valves set to. They can be set to skimmers+bottom drains, skimmers only, bottom's only, or vacuum ports only, and the bubbles continue. I've bleed air off the top of the sand filter and even rebuilt the piping a second time to be sure I did it right. I'm not able to solve this problem myself and the only help here in Cancun is self taught laborers and we have a language barrier because my Spanish is poor at this time. Every thing on this pool is manually controlled. I think that the sudden piping failure somehow has caused this, but cannot figure it out. Any suggestions or advice would be much appreciated. I've read all the treads previously posted and have checked everything they did to no avail. See the pix below.
Overall view of system:
Piping manifold w/valves: