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1-1/2" FBT x 2" MBT Union Adapter w/o o-ring 50100120 - Bubbles Supply

1-1/2" FBT x 2" MBT Union Adapter w/o o-ring 50100120

Part #: 50100120

$5.47
In stock — ships today
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About this seal/gasket

This 1-1/2" FBT x 2" MBT union adapter is an authentic Aqua-Flo by Gecko replacement part designed for spa main pump connections. The threaded union features a female buttress thread on one end and male buttress thread on the other, creating secure plumbing connections in hot tub circulation systems. Note that this adapter does not include an o-ring, which must be purchased separately.

Manufactured to OEM specifications, this union adapter ensures exact fit guaranteed with your Aqua-Flo pump assembly. We ship same-day from our Canadian warehouse and back every part with a full 1-year warranty for complete peace of mind. When installing, hand-tighten the union connections first, then use a strap wrench to achieve final tightness—avoid over-torquing which can crack the plastic threads.

Exact part number

50100120

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Also known as / Replaces

This part replaces or is interchangeable with:

  • buttress thread union
  • FBT x MBT adapter
  • pump union adapter
  • spa pump union connector
  • union fitting

Looking for an older part number? Check our supersession lookup tool

Technical specifications

Union size
1-1/2 inch female buttress thread inlet x 2 inch male buttress thread outlet

Plumbing notes

  • Union size: 1-1/2 inch female buttress thread inlet x 2 inch male buttress thread outlet

Need help measuring? Email hello@bubblessupply.com with a photo of your existing plumbing.

Common symptoms this part fixes

If your spa is showing any of these signs, this part is likely your fix:

  • Water leaking at pump union connection
  • Cracked or cross-threaded union fitting
  • Union won't seal even with new o-ring
  • Stripped buttress threads causing weeping leak
  • Union adapter broken during winterization or service

Not sure if this is your problem? Try our diagnostic centre or .

Before you buy — quick checklist

  • Confirm your existing union has a 1-1/2" FBT on the plumbing side and 2" MBT on the pump side — do not assume by pump size alone
  • This adapter does NOT include an o-ring — order the correct o-ring separately before starting the job
  • Inspect both mating surfaces for cracks or debris that could prevent a proper seal even with a new adapter
  • Verify this is an Aqua-Flo branded pump — buttress thread profiles are not universally interchangeable across pump brands
  • Check whether your union body (the outer collar) also needs replacement or if the adapter alone is the failed component

Reading the checklist now prevents 90% of returns. Worth the 60 seconds.

Install difficulty: Easy — DIY-friendlyTypically 15-30 minutes

What's in the box

  • 1-1/2" FBT x 2" MBT union adapter (1 piece)
  • O-ring not included — must be purchased separately

If your order is missing any items listed above, contact hello@bubblessupply.com within 48 hours of delivery.

Warranty

1 year manufacturer warranty against defects

Covers manufacturing defects. Does not cover improper installation, normal wear, or accidental damage.

Warranty claims: warranty@bubblessupply.com

Perfect Fit Guarantee

Ordered with our help and the part doesn't fit? Contact us before installation. We'll resolve it with an exchange, replacement recommendation, or return approval.

Learn about our Perfect Fit Guarantee →

Shipping

We ship across the US and Canada. US orders ship from our US warehouse to US customers; Canadian orders ship from our Canadian warehouse to Canadian customers — no cross-border shipping, no surprise duties. In-stock orders placed before 3pm CT ship same day. Standard shipping $9.95 flat rate. Free shipping on orders over $200. Express options available at checkout.

Returns

30-day hassle-free returns on unused parts in original packaging. Contact us before returning to receive your RMA number.

Frequently asked questions

Check the Compatibility section above to confirm fitment for your spa brand and model. If your model is not listed, use our fitment selector at /pages/find-my-part or ask our parts AI for a personalized recommendation.

In-stock orders placed before 3pm CT ship the same day. You will receive tracking information by email as soon as your order ships.

We accept returns within 30 days of delivery for unused items in original packaging. Email returns@bubblessupply.com with your order number to start a return. Installed electrical parts cannot be returned for safety reasons.

Yes, all new parts come with a 1-year warranty against manufacturing defects. Warranty does not cover damage from improper installation or normal wear and tear.

Customer reviews

AI Fitment Assistant

Tell us your spa model and we will confirm this part fits before you buy.

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