Pipe Sizes for Spa air lines


New member
Feb 11, 2015
Baton Rouge Louisiana
Moved from here.
I was under the impression that all IG spa jets have a venturi of some sort. It would be short of impossible to mix air with pressurized water otherwise.

In most cases, a blower is used when the air line is too long for just a natural venturi so the air intake is insufficient for the jet. Also, the force of the jet is caused by the water pressure and not by the blower or air. A blower simply makes more bubbles.

WARNING: Don't let the PB use less than 2.5" pipe for the spa or you might end up with weak jets. With a 2 HP I would even go with 3" pipe.
2 1/2 to 3 inch plumbing is exactly right. But as far as air blower because airline is long. Venturi can pull air from a long airline just fine. In most cases air blowers get put on top of the air pipe because the Venturi nozzle body insert do not have a good seal. The one inch pipe Hass to be cut the correct lenghth so that the threads can be threaded inside to where the O-ring seats like it supposed to Only one of them has to lack a good seal to make the entire group of them not work. So all the inserts need to be installed with a good seal. As well as the final and last installation Venturi jet return fittings/nozzles..

ever have a problem with water shooting out of the spa side air control knob. And you just have to screw it closed all the way to keep water from coming out of it. It’s because of everything described above regarding having a good seal
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TFP Expert
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May 3, 2007
Pleasanton, CA
Pool Size
Salt Water Generator
2 1/2 to 3 inch plumbing is exactly right. But as far as air blower because airline is long. Venturi can pull air from a long airline just fine.
First, you know that this is a very old thread right (2011)?

Second, I think you may have misinterpreted what I had posted. As long as the air line is horizontal or tilted upwards away from the spa or a Hartford loop is installed, then I agree that the length of the air line should not matter. However, if the air line is tilted slightly downwards and no Hartford loop is installed, which seems to be fairly common at least on this site, the depth of the water increases with increasing air pipe length and since venturis have only a finite amount of suction based upon their geometry, the lift is going to be limited so either it takes a very long time to evacuate the air line or it may not evacuate at all which is why a blower is necessary.

Also, the standard venturi tees have no o-rings. I think you are talking about venturis like the Polystorm. Even so, the leak would have to be extremely bad for the venturi action to be affected.
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