Clear Water

CW-100 External Algae Scrubber

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Solve your nutrient & algae issues with an Algae Turf Scrubber from Clear Water Scrubbers. Algae scrubbers can save you money and time with the minimal maintenance and energy usage. 

Dimensions - 13 3/4" L x 9" W x 9 1/4" H

  • Easy to harvest
  • Safe design
  • Simple to plumb
  • Quality acrylic construction
  • Multi-directional input barb


Algae turf scrubbers use natural growing algae to combat nutrients and have been used for many years now with great results. Many reefers that have been using them do not use any type of protein skimmer or expensive phosphate removal media to combat nutrients because scrubbers work very efficiently and can be added to almost any saltwater or freshwater system. As algae grows it will "lock" up nutrients in its structure and harvesting the algae you are basically removing nutrients and other undesired chemicals from your tank 


Clear Water Scrubbers are an external design that needs to be mounted higher than the sump of your tank for the drain to flow into. The feed for the scrubber can be done with a stand-alone feed pump, manifold, or through the drain of your aquarium and plumbed into the included 1/2" barb fitting. Water will then flow over the algae screen that is blasted with high power red/blue LED lights that encourage algae growth and then the water will flow into the main drain fitting and down into your sump. Clear Water's scrubber was designed with a 1/2" emergency drain fitting that will accept any excess flow if the 1" main drain ever gets clogged with algae. 


Maintaining the scrubber only takes a few minutes every one to three weeks to harvest the algae that has grown on the screen. By removing the horizontal union and rinsing the screen under a faucet will help knock a majority of the algae off the screen to be disposed of. Removing all the algae from the screen will lead to a slow start of the next batch and by leaving a small amount of algae on the screen you will help seed the next batch allowing it to grow faster. You may need to use a soft bristle brush (toothbrushes work great) to clean the slot that the screen fits into every now and then also. 



Max Recommended Tank Size - Up to 200 gallons

Dimensions - 13 3/4" L x 9" W x 9 1/4" H

Screen Dimensions - 7" x 6 3/4"

Recommended Flow Rate - 350 GPH

Input Barb Size - 1/2"

Main Drain Bulkhead - 1"

Emergency Drain Bulkhead - 1/2"

Power Consumption - 40W @ 120VAC


What's Included?

1x CW-100 External Algae Scrubber

2x Replacement Screen Clips


Clear Water Scrubber Sizing Recommendations

Oversizing an algae scrubber does not necessarily mean that it will grow algae faster or be more efficient, and in some cases, we have found oversizing the scrubber too large, can lead to poor results.

Model Screen Size Aquarium Size
CW-50 6" x 6" 60-100 gallons
CW-100 7" x 7" 120-200 gallons
CW-200 10" x 8" 180-400 gallons
CW-300 11.5" x 10.5" 400-1000 gallons


Installation Instructions:

1. Find a suitable place for the scrubber to be placed that allows it to freely drain into your aquariums sump. 

2. For best results remove the main and emergency drain bulkheads and install them in reverse (flange and gasket inside of the scrubber body).

3. Using 1" soft tubing or PVC plumb the drain into your sump. 

4. Plumb the emergency drain with 1/2" PVC or soft tubing allowing it to drain into your sump. We prefer to keep the emergency drain a few inches over the water level making the water crash into the sump that produces an audible noise, letting you know when something is not correct with the main drain.

5. Attach 1/2" soft tubing to the included feed barb fitting. We really like using soft silicone tubing for this application. 

6. Adjust the flow over the algae screen so that an even sheet of water flows down the screen. Flow adjustments can be made with either a ball valve on the feed line or with a DC style pump. 

7. Plug the LED light power cord into a timer or aquarium controller and program it for a 12-hour daily photoperiod. We suggest illuminating the algae scrubber in an opposite lighting cycle than your display tank to help stabilize your aquarium pH. 

8. Monitor the algae growth and after a few weeks, algae will be ready to harvest!


Note - For feeding the scrubber we prefer to use a stand-alone feed pump since they can be fine-tuned to the algae scrubbers needs. We really like to use DC pumps that let us control the flow rate through a controller or an AC pump with a ball valve. 

More Information
UPC 860266001407
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Product Questions

How many amps does this use?
Question by: Brooke Jisha on Jun 20, 2022, 6:32 PM
Thanks for asking. The scrubber uses 40 watts at 120ac, which comes to about .33a.
Let me know if you have any other questions, and have a great day.
Answer by: Chad (BRS Staff) on Jun 28, 2022, 8:20 AM
How is a "cube" defined exactly?
Question by: Nate Renner on Apr 2, 2020, 10:55 AM
Hi there,

It is referring to the amount of frozen food cubes you can feed a day.

Take care
Answer by: Thomas Billington on Apr 2, 2020, 3:53 PM
What do you recommend when it comes to attaching a barb to the emergency drains. Any thread sealant needed?
Question by: Michael on Jan 25, 2019, 1:25 PM
Hey there! What I use on mine is a spigot 90 elbow with a barb inserted in that. The emergency has no barb to allow water to drip out and make a splashing noise to indicate an issue.

Take care!
Answer by: Thomas Billington on Jan 30, 2019, 11:42 AM
Can you recommend a pump to go along with this scrubber?
Question by: John Marx on Aug 29, 2018, 10:16 PM
Hey there!

It only needs 350 GPH so we would recommend using a Sicce Pump, specifically the Sicce 1.5. If you end up using your scrubber farther than a few feet from the pump you will need to get a bigger pump like the Sicce 2.0.
Answer by: Thomas on Aug 30, 2018, 2:03 PM
I am debating whether to set up this or a refugium with marine pure blocks and cheato in my 90 gallon system. Is it possible to run them both with success (I would like the refugium to grow pods too) or will it have to be one or the other? Which one would be more efficient at nutrient export? I plan on having about 8 fish with LPS and SPS corals. Thanks!
Question by: Ethan Sooklal on Jan 27, 2018, 2:47 PM
Using both methods would eventually create competition for nutrients and more than likely the refugium and algae scrubber will not perform well. We would suggest choosing one method. The refugium definitely would be our ideal choice, but if you are tight on space the algae scrubbers are super efficient and compact, but will not be that great for copepod production.
Answer by: Charlie on Jan 30, 2018, 5:10 AM
Has there been any studies on how much more evaporation/ro water will be needed in say 100 gal tank since this increases air to water contact more than normal. I am curious as to how much more RO water for top off I will need per day and therefore $$ of media and cartridge changes on RO unit more often?
Question by: Bryan Smith on Dec 31, 2017, 12:58 PM
Thanks for contacting BRS!

We do not know of any such study to confirm or deny that. Certainly is something to look into! Have a great day.
Answer by: Josh Cuta on Jan 8, 2018, 11:36 AM
Can this be used with a tank that doesn't have a sump?
Question by: John on Sep 15, 2017, 10:56 AM
Technically, yes. While a sump makes a very convenient place to locate and plumb an ATS into, so long as you have a way to push the water to the ATS, and then a way for the water to drain freely back to your tank, there's no reason you couldn't do it. That said, if you located the ATS above your display, for instance, and allowed it to gravity feed back down, having it outside of a cabinet may have more water noise than you like, and when the light it on, preferably at night, you'll have a red glow coming from the LEDs that light the algae. We have had some people at the office talking about hooking one up on the back of their all-in-one though!

Happy Reefing!
Answer by: Zack on Sep 15, 2017, 3:39 PM
What type of maintenance for the white pad shown in the pictures. Are there replacements if needed?
Question by: Tom Li on Sep 15, 2017, 8:45 AM
Hey there,

While you could technically replace the screen material if it were somehow damaged, it's a very durable plastic mesh and should not ever wear out. The material is a roughed up mesh that allows the algae to adhere to it, and does not need to be completely cleaned during maintenance. It's best to just remove the majority of the algae during cleaning, and leave a portion on the screen to allow for rapid re-growth. I've had mine running on my tank for 2+ years and the mesh shows no signs of degrading.

Happy Reefing!
Answer by: Zack on Sep 15, 2017, 3:45 PM