Problem with Microsilk on Marquis Promise

[Hagman62]

I have had a Marquis Promise for almost three years and love it.  My wife particularly loves the microsilk option.  Unfortunately I now have a problem with it, When running microsilk it only produces bubbles for about 10 seconds.  The pump continues to run but no bubbles come out.

I opened the side up to investigate and am 90% sure I have identified the problem.  There is water in the air intake line for the microsilk pump.  When you turn on the microsilk pump, you can see the water in the airline being drawn towards the pump, but it never pulls it all the way down.  I tried to pull the tubing off at the air intake fitting but it was on so tight I could not get it off.  The other end of the tubing appears to go to the microsilk pump on the intake side, but it is concerned in spray foam and I can’t get to the fitting where it connects.

Any suggestions on what to try?  Would draining the hut tub clear this line?  Thanks for your help

[Hagman62]

Anyone?  Any suggestions to try?

[Hagman62]

Ended up needing a new microsilk pump

[Mrfixit]

I have the same problem with the Microsilk pump on my Marquis spa.  I pulled the pump and opened the casing and found the rotors and impeller were not keyed to the shaft.  All are plastic and it appears the keys are molded as part of the rotors and impeller and have worn/broke off.

The spa was purchased in 2017 and that winter during a very cold period in February (Wisconsin, - 10-20F for multiple days), the line to the Microsilk pump froze and broke.  Marquis had a modification that involved monitoring the temperature on the pump suction line and automatically running the pump for a short period of time to bring warm water into the piping.  That was five years ago and seemed to solve the problem.

I’m wondering if that event compromised the pump and eventually led to the failure.  No way to tell.  I’ve heard the pumps have been generally reliable.

Has anyone experienced the freezing issue with the Microsilk pump followed by pump failure in the future?  I’m planning to purchase a new pump as I can’t find replacement parts.