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The age of the spa would be helpful, but my guess would be 2008. Your symptoms seem to relate more to the pump being on high or low, not so much the air controls, although they may be part of the symptom your describing.There are large 2" check valves on the suction side of each pump that open and allow water to be drawn into the pump. It sounds like one of the "flapper" gates has become seperated and is free floating inside the check valve body. Your problem relates to 1 specific pump, #1, #2, or #3. The purpose of the check valve is to not allow the other pumps to draw water backward from other pumps. You need to isolate, or identfy, which pump is involved and replace the 2" check valve, usually within 2 feet of the suction connection of the affected pump, possibly within the foam.
JJ, you are correct, they are not 2 speed, but they are variable pressure from low to hi.Matt, I am not correct about the check valves, your model does not use them, however the "variable (speed) pressure" of the jets is produced by controlling the water flow at the pump. At the lower end of the spectrum it is causing cavitations in the operation of the pump which is producing an air mix within the pump at the lower water supply pressure. The cavitations do stop when the pumps are at a full draw and operating at peak pressure. And yes, this is predictable performance when the pump has a small amount of water to move at the same RPM'sTo JJ's credit, when in doubt, check with Bob. We learn something new everyday.
...And yes, this is predictable performance when the pump has a small amount of water to move at the same RPM's
Quote from: clover on June 01, 2012, 12:31:45 pm...And yes, this is predictable performance when the pump has a small amount of water to move at the same RPM'sIs that really so? Because the pumps draw less electricity when you change the directflow valves..that would indicate to me that it is running at a lower RPM? From the sound of it it also changes the speed?
Yes, it's the same rpm but when you lower the waterflow the pump needs less power. And I got confirmed that it is expected that a certain amoumt of air is mixed in though the service guy thought that a air valve gasket was bad and this made some extra air being mixed in.