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CPR CS90 Aquarium Overflow Box

Was: $169.99
Now: $144.49
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CPR CS90 Aquarium Overflow Box

A built-in overflow is the most efficient method of draining aquarium water to a filter. If your aquarium does not have built-in overflow, CPR Continuous Siphon Overflows/Prefilters are the best means for getting water from an aquarium to a filter system without expensive modifications to the tank. They quietly skim up to six times more water than units with tubes.

The advantages of CPR Continuous Siphon Overflows/Prefilters include:

  • Adjustable water level allows you to easily change the level in your tank. 
  • Black top reduces algae growth. 
  • Quiet operation. 
  • CS Overflows feature a grated inlet.



  • Model: CS90
  • Flow Rate: 600gph
  • Outflow Size: 1" Bulkhead



  • (1) Overflow body
  • (1) Screen and sponge
  • (1) Vent tube with small “O” ring
  • (1) Bulkhead assembly
  • (3) Adjustment screws
  • (1) Air line
  • (1) Aqua Lifter pump and Acrylic Lid (included in Deluxe models)


Product code: 27
Item No. OF-CPR-CS90

1 Review

  • 5
    CPR CS90 Overflow

    Posted by Camoreefer on Jul 2nd 2021

    I have a 54-gallon corner bowfront tank that is not drilled for a sump. I’ve been running a Fluval 406 canister filter for 1.5 years since the tank’s inception, but I grew tired of having to clean the canister twice per month to keep my water quality high. Finally upgraded to the CPR CS90 Overflow and its awesome! Having the security of the continuous siphon makes me feel much better if we experience a power outage. Partnered this overflow with a Trigger Systems Sapphire Cube Sump with an Ecotech Vectra S1 as my return pump. The system is working flawlessly! I highly recommend ordering the lid for the overflow box to reduce noise and salt creep. Super happy with CPR’s product. I have their hang-on-back AquaFuge2 Refugium. Quality company!