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Aquarium Supplies
Home » Saltwater Aquarium Supplies  » Overflow Box  » External Boxes  »  CPR CS90 Overflow Box
CPR CS90 Overflow Box

CPR CS90 Overflow Box

In Stock: Buy now and your order will ship the next business day
Item #:
MSRP: $144.95
You Save: $30.96 (21%)
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CPR CS90 Overflow Box Information

Product Manuals & Documentation

  • For glass or acrylic aquariums up to 125 gal.
  • Flow rate 600 GPH.
  • 8" wide
  • 1" bulkhead outflow
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.
Tip: We recomond the use of an Aqua Lifter pump with the CPR overflows for trouble free operation. Another alternative is to hook the bleed hose from the overflow to the air intake of a power head. This way the overflow will continue to wok if it drawes some air into it or in the event of a power failure it will restart.

What's in the Box

  • overflow box
  • overflow screen
  • 1" bulkhead
  • 1" slip strainer
  • foam ring for drain
  • 8" piece of airline tubing
  • air release tube for drain


Manufacturer Info

CPR Aquatic Aquarium Supplies
In Arcata, located in Northern California, the sea is a way of life. From the advanced Marine Biology department at Humboldt State University, just up the hill from CPR’s headquarters, to Humboldt Bay, about a mile west, CPR is nestled in a perfect environment to develop equipment for marine aquariums. CPR was started in a small garage in 1987 to produce biological filters for local aquarists. People who used CPR filters were impressed by the high quality and affordable prices. Word spread and the company grew. Since then, CPR has expanded to a 10,000 sq. ft. production facility and has developed many innovative products over the years. CPR is incorporating new ideas and technologies all the time. Their goal is to allow aquarists to place the highest performing products in their tanks at reasonable prices.


1 year manufacturer warranty.  All warranty services are provided by the manufacturer.

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CPR CS90 Overflow Box Reviews

Average Rating
(135 reviews)
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of 14


Reviewers Rating Average

Posted: 5/9/2014 from BLAINE, WA UNITED STATES
2.5 5
Experience Level: Intermediate

Comments: The cs50 does NOT come with ANY way of connecting the tubing to the unit. It's a nice overflow, but a headache to deal with. Won't purchase from this manufacturer again.

1 of 1 People found this review helpful, did you? Yes No

Needs a dosing pump

Reviewers Rating Great

Posted: 4/9/2014 from CONCORD, NC UNITED STATES
4.0 5
Experience Level: Intermediate

Comments: I finally installed this overflow on my system and I do like it better than the U-tube design I had previously. The only downfall is that you will need a pump to keep the air bubble from appearing in the overflow area.

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Reviewers Rating Excellent!

5.0 5
Experience Level: Intermediate

Comments: This overflow is the best you can buy! You need the aqualifter pump with it so do not try to use it without it. Hook it up turn on the pump and your moving water. I do not want to drill my tanks and this was my best option.

1 of 1 People found this review helpful, did you? Yes No

overflow box

Reviewers Rating Excellent!

Posted: 3/27/2014 from VACHERIE, LA UNITED STATES
5.0 5
Experience Level: Beginner

Comments: Love it

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Reviewers Rating Unsatisfactory

Posted: 3/26/2014 from North Wilkesboro, NC UNITED ST
0.5 5
Experience Level: Expert

Comments: I hate this box and the tom's aqua lift. I will never buy another one that doesn't have U tubes in it. Put this CPR overflow box with toms aqua lift on my 125 gallon reef tank. When I set my two mp40's on in wave mode the movement of the water is to much for this style box. It's always getting air in it and stops the overflow. I took a double U tube box off a tank I'm not using tonight and now I can run my mp40s wide open without lose of suction. I give the CPR overflow box and toms aqua lift the worst two thumbs down I can. Don't buy either of these if you plan on upgrading to a wavemaker. Bty even without the wavemaker you still can't trust the toms aqua lift to not stop working while your away from home, so beware that you might come home to a wet floor one day.

0 of 5 People found this review helpful, did you? Yes No


Reviewers Rating Unsatisfactory

Posted: 2/16/2014 from ROCKAWAY PARK, NY UNITED STATE
0.5 5
Experience Level: Expert

Comments: Hate isn't a strong enough word for how I feel about this product. No matter what the height, flow rate, adjustment of air tube or removal of air in the top of the chamber, this is the noisiest overflow box ever made. It sounds like Niagra falls in my living room and I cannot get it to stop, no matter what I change. I don't even enjoy my reef anymore and it's solely because of this box. DO NOT waste your money on this garbage. Wish I never bought it.

1 of 7 People found this review helpful, did you? Yes No

Works great

Reviewers Rating Excellent!

Posted: 2/12/2014 from SARATOGA, CA UNITED STATES
5.0 5
Experience Level: Intermediate

Comments: I have this on an older 70 gallon tank that didn't have a builtin drain.

0 of 2 People found this review helpful, did you? Yes No

Workable Product

Reviewers Rating Excellent!

Posted: 1/26/2014 from REDMOND, WA UNITED STATES
5.0 5
Experience Level: Expert

Comments: I am using this overflow on my homemade drip filter and works fine. The only issue is debris from the tank either getting caught in the intake or on the sponge.

1 of 1 People found this review helpful, did you? Yes No

Hard to clean

Reviewers Rating Great

Posted: 1/21/2014 from NORTH BEACH, MD UNITED STATES
4.0 5
Experience Level: Intermediate

Comments: Box works well. MUST USE some type of syphon pump. Only problem I've found is difficulty in cleaning the very top inside. Would be nice if box came with flexible brush or comparable cleaning tool. But over all.... Best overflow box I've used.

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cpr overflow box

Reviewers Rating Great

Posted: 12/12/2013 from NEWARK, DE UNITED STATES
4.0 5
Experience Level: Intermediate

Comments: I like it but did not like the fact that you need a somekind of pump to pri m the thing

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of 14
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