16″ Shadow Overflow V1 to V3 Rear Box Upgrade Kit


Shadow V3 Upgrade Kit. You must own the V1 Shadow Overflow in order to purchase this. Please contact us prior to ordering. 



In stock (can be backordered)

Save by adding these items to the Cart with the Shadow Overflow now!

Used for drilling 3/4″ Return bulkhead hole in tank.

SKU: Rear-Box-Kit-Shadow16V3 Category:


The V3 Shadow® Overflow Rear Box Upgrade Kit.

New Features of the V3 Shadow® Overflow

  • New Sealed Rear Lid and Rear Box Design – Redesigned Rear Lid and Rear Box flange makes a watertight seal. This helps eliminates any salt creep issues that may have formed with the V1 Shadow®.  We have designed the V3 Rear lid and Rear box to be virtually watertight and prevent salt creep and water from exiting the box.
  • Exterior Box Slip Fitting Openings Modified – We have modified the 3 x 1.5″ Slip fitting openings in the rear box to allow for better fitting of ANY 1.5″ PVC Pipe or Fitting. This means that you can now dry fit your PVC Pipes into the rear box holes without any worry of damaging the overflow that may have happened with the V1 Shadow®.
  • Re-Engineered Polymer Construction – The Rear Box Material has been changed to a proprietary new polymer blend! This new polymer allows you to use ANY type of PVC or ABS glue or primer you choose. V1 Shadow® needed special PVC glue to work, not anymore! This means that you can use any PVC Cement that you can find locally or have on hand already. It also makes the rear box even more durable than before!

It is still 100% Injection Molded for the highest quality and most precise fitment! Easy to install and very low profile. Check out the specs of this overflow system. It can be used with as little as 400 gph all the way up to 2500 gph. If you need more flow, just add a second box.


What’s Included in this Kit: This is an UPGRADE KIT ONLY. 

1 x New V3 Rear Overflow Box
16″ x 3.75″ x 7″ Injection Molded Seamless Translucent Black Hi-Tech Polymer
3 x 1.5″ Slip fittings for easy plumbing with standard 1.5″ PVC Fittings

1 x New V3 Sealed Rear Lid
Water Tight Locking Rear Cover
– Our poly-carbonate rear box cover is not just a rectangle piece of material. It is a feature that was specifically designed to have a function and structure. The V3 Rear Lid makes the rear box water tight with the new channel system. This helps to keep water inside the rear box, preventing salt creep.



Additional information

Weight4 lbs
Dimensions18 × 10 × 10 in

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