CPR Aquatics

Retrofit Overflow Box with Backing

Grouped product items
RSS05DX Extra Small Overflow Box with Backing

SKU: 208184

In stock

Discontinued by Bulk Reef Supply

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RSS07DX Small Overflow Box with Backing

SKU: 208185

In stock

Discontinued by Bulk Reef Supply

- +
RSS24DX Extra Large Overflow Box with Backing

SKU: 208188

In stock

Discontinued by Bulk Reef Supply

- +

An overflow box is a great way to keep the water level at a constant in your saltwater aquarium as well as increase the rate at which surface water, and the film and dust with it, is removed. CPR Aquatics are high quality, black acrylic and built in the USA. Install by using a bulkhead. Bulkhead size will determine your flow rate.

Sizes Available

  • Extra Small - up to 250 GPH
  • Small - up to 500 GPH
  • Medium - up to 900 GPH
  • Large - up to 1200 GPH
  • Extra Large - up to 1600 GPH


Sizes Available

  • RSS05DX - 6 3/8" L x 2 5/8" W x 3 5/8" H (Nano tank)
  • RSS07DX - 5 1/4" L x 3 7/8" W x 5 1/4"H (Up to 60 Gallon tank)
  • RSS12DX - 7 1/4" L x 4 1/4" W x 5 1/4" H (Up to 120 Gallon tank)
  • RSS18DX - 12 1/2" L x 4 1/4" W x 5 1/4" H (Up to 200 Gallon tank)
  • RSS24DX - 18 5/8" x 4 1/4" W x 5 1/4" H (Up to 300 Gallon tank)


When choosing an overflow we suggest using the largest overflow box that will fit your tank. It is impossible to oversize an overflow.

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Product Questions

What bulkhead do you suggest is best to attach overflow to tank? and does it come with the extra gasket required to make connection?
Question by: Christopher Taddonio on Jun 7, 2017, 10:04 PM
Both ABS bulkheads and Schedule 80 will work for this type of installation. If you expect there to be any pressure on the bulkhead itself (this should be kept to a minimum), the Schedule 80 might be best as it is more robust and the gaskets are thicker. There isn't normally a need to install an extra gasket between overflow and tank, and the seal of the bulkhead and nut tightened through the overflow and tank should be sufficient.

Have a great day!
Answer by: Zack on Jun 13, 2017, 8:15 PM
So what else do you need to order to install it.
Question by: Jacob on Jul 10, 2016, 3:35 PM
Hi Jacob,
To install the CPR overflow box, with backing you will need a proper plastic drill bit to drill through the acrylic overflow, as well as a diamond coated drill bit for the aquarium you will be placing it on. The drill bit size will be dictated by the plumbing size, and bulkheads that you choose to place in the overflow. We would also suggest using a small amount of silicone to seal the backing of the overflow to the tank as well to minimize any leaks between the multiple layers of materials.
Answer by: Charlie on Jul 11, 2016, 10:03 AM
Can you achieve quite overflow with one of these ? Can multiple drains fit in the overflow box?
Question by: David on Mar 15, 2016, 2:10 PM
Great question!
This can be silent if the herbie method or bean animal is used. They can accept multiple pipes depending on the size of the bulkhead used. You will want to measure the bulkhead width and make sure more than one will fit in the width of the overflow. Feel free to let us know if you have ny further questions!
Answer by: Connor on Mar 15, 2016, 6:58 PM
Does this need to be siliconed to the tank, or will just a bulkhead hold it in place?
Question by: Earnest on Aug 2, 2014, 6:33 AM
Hi Earnest,
If you use an extra gasket for the bulkhead between the overflow box and tank then you would not need to use any silicone, the bulkhead itself would hold the box in place.
Answer by: Bulk Reef Supply on Aug 2, 2014, 6:33 AM
What size overflow box would I need for a 46g bowfront tank?
Question by: Bob on Mar 25, 2014, 6:52 PM
Hi Bob,
The biggest factor is what type of plumbing you plan to put inside of it (and then just make sure you get an overflow large enough to fit it) but for a simple drain on a 46g tank the RSS07 Small should be plenty fine.
Answer by: Bulk Reef Supply on Mar 25, 2014, 6:52 PM