Air coming from return...no air in suction

[redman1978]

Im having an issue with a pool thats driving me nuts and I need help. I have a client that is getting small air bubbles mainly out of one return, although i have witnessed it out of others and the spa jets. It has an Intelliflo VS3050. The bubbles are only present on low speed (about 900 RPM). This is a pool/ spa gunite, easy touch system, three way pentair valves on suction and return side. FNS plus DE filter with Hi flow valve, Master temp heater with a bypass and a polaris 280 with booster pump. Also a blue white digital flowmeter and intellichlor salt.

I have been through this system with a fine tooth comb! There is no air in the suction lines, no air in the pump basket, I have a clear check valve in the pump discharge before the filter with no air and a sight glass in the return after the heater and flowmeter but before the spa / pool valve... no air in this either. I have pressure tested all plumbing... no leaks.

Any ideas????????????

Thanks

 

[mas985]

intellichlor salt

SWGs produce hydrogen bubbles and they are more noticeable at low speed.

BTW, Welcome to the forum.

 

[redman1978]

Thanks for the welcome. I completely forgot about that. I emailed the customer and asked him to turn off the intellichlor or unplug it and wait about 30 min to see if the bubbles stopped. He just got back with me and the air is still present. Im at a loss!

 

[duraleigh]

Well, let's see....air cannot get in to the system from the pressure side so that eliminates everything after the pump. There somehow may have been some air trapped in the top of the filter that was slowly bleeding off but it can't get in from that side.

Air only gets into the system from the suction side. So, starting with the skimmer, visually watch to see it's not slurping air. Then move to the next joint, then the next, etc. Pay particular attention around the pump basket o-ring and the pump strainer basket drain plug.....a leak there may be very difficult to see. Next most common place is a faulty valve, etc. etc.

A crack somewhere in the pvc pipe itself is possible but is about the least likely.

It is somewhere on the suction side of the system.

 

[anonapersona]

Since I've just done a ton of reading in the forum about this...the plug at the bottom of the pump can leak air that gets sucked in without gathering at the site glass. Also check the threaded connections, if teflon used instead of pipe dope or silicon lube may leak air. Someone said to check the diffuser O-ring in the pump. Check the connection to the pump, threaded inlet connection.