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Polaris 3900 Sport Water Management Assembly w/ O-Ring | 39-300

Polaris SKU: 39-300

Polaris 3900 Sport Water Management Assembly w/ O-Ring | 39-300

Polaris SKU: 39-300
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Polaris 39-300 Water Management System (WMS) Assembly with O-Ring – For Polaris 3900 Sport

The Polaris 39-300 is a replacement Water Management System (WMS) assembly (includes O-ring) for the Polaris 3900 Sport pressure-side pool cleaner. The WMS is a key internal water-routing component that helps direct incoming water through the cleaner’s intake/jet channels to maintain strong pickup and consistent cleaning performance.

Key Features

  • Part Number: 39-300
  • Part Type: Water Management System (WMS) assembly
  • Includes: O-ring (for a proper seal during installation)
  • Compatible Cleaner: Polaris 3900 Sport
  • Function: Directs water flow inside the cleaner to support strong debris intake and stable movement

Common Signs It’s Time to Replace

  • Cleaner has reduced suction/pickup even with good pressure and a clean wall screen
  • Inconsistent performance (surging, weak intake, or poor debris collection)
  • Cracks, warping, or visible damage on the WMS body
  • Water leakage at the WMS sealing area (flattened or damaged O-ring/sealing surfaces)

Installation Notes

  • Shut off the booster pump and remove the cleaner from the pool before servicing.
  • Install the WMS assembly in the same orientation as the original part.
  • Ensure the included O-ring is seated properly and the sealing surfaces are clean before reassembly.
  • After reassembly, verify the cleaner operates smoothly and debris pickup is restored.

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Installation & Maintenance Tips

  • Clean the wall fitting screen/filter regularly—restricted flow can mimic internal cleaner problems.
  • Rinse the cleaner after heavy debris events to reduce grit buildup that accelerates wear on internal water-routing parts.
  • Use only a light film of silicone lube on O-rings to improve sealing and reduce pinching during assembly (avoid petroleum grease).
  • If performance is still weak after replacement, inspect feed hose sections for pinhole leaks and confirm proper booster pump pressure.
Questions about returns? View our return policy.

Hours Of Operation:

Monday - Friday: 7:00 am to 5:00 pm Phoenix Time

Saturday: 8:00 am to 2:00 pm

Sunday: Closed

  • We do not ship on Saturday or Sunday.
  • Orders totaling more than $300 will require signature confirmation upon delivery.
  • We process and prepare orders for shipment within 1 business day. Please note that many other pool supply retailers require 3–5 days of handling time before shipping.
  • Orders placed after 1:00 pm Phoenix Time may not be eligible for same-day shipment.
  • Expedited shipping options are available at checkout.

Return Policy:

  • Products that are received damaged will receive a refund in store credit.
  • Most products are eligible for return within 30 days of receipt, except where noted below.
  • To initiate a return, please complete an RMA form prior to sending your item back.
  • Original shipping costs are non-refundable and will be deducted from the return credit.
  • Items returned missing accessories or original packaging, or that are not in the same condition as received, may be subject to a restocking fee of up to 100% depending on the condition of the item upon return.
  • Some returns will be charged an automatic 15% restocking fee.
  • We are unable to issue refunds for items that have been damaged or rendered inoperable due to installer error.
  • Please complete the return form to receive your RMA number and return shipping label.
  • Chemical products are not eligible for return under any circumstances.
  • The Pentair Colorsync 618031 is not eligible for return.
  • Pool cleaners are not eligible for return.
  • Opened seals and o-rings are not eligible for return.
  • Capacitors are not eligible for return.
  • Plastic popup tools are not eligible for return.
  • Automation components and circuit boards are not eligible for return.
  • If a light is returned due to a reported malfunction and is found to be fully operational upon testing, return shipping costs and a restocking fee will be deducted from the refund.
  • Orders refused at the time of delivery will be subject to the original shipping costs being deducted from the refund.
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