Algae Scrubber DIY




Keeping fish alive in the household environment is not an easy thing to do. The most frustrating part of this hobby, in fact, is the algae problem. If we do not change water on time(as the experts always recommend us to do), the algae will be everywhere! From the bottom of the tank to the side, from leaves of the water plants to the decorations in the tank, they are like ghosts flowing around growing on anything they can attach itself to! It affects the appearance of the tank, and it also indicates the unhealthy water condition the fish are living in. Basically, it is bad. I have been fighting with this problem since the second week I went into this hobby. After a long time spent researching for the solution of this problem, I came across the idea of algae scrubber. The idea is simple: if algae loves to grow, and grow in such a rapid speed, we just need to create the perfect environment for them to grow. However, let them grow out of our tank where we can clean them easily. Therefore, build a plastic container with better lighting than the tank, cycling the water on a piece of plastic net, which creates a waterfall effect to grow the algae. Every week we clean the algae on the net off, and we never have to worry about changing the water anymore. For more information about the algae scrubber, please visit That is where I learned so much about this project! Sounds exciting, right? Lets get started!

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Step 1: Heat Sink for Led Lights

Old CPU heat sink * 4 pieces of binder clips * 4 pieces I connected them in such way(shown in the pictures), since I have no professional tools.

Step 2: Connecting Heat Sink by Bander Clips

Step 3: Preparing LED Lights Installation

Proxy glue was used for gluing the LED lights to the heat sink.

Step 4: About the Lights

Glue the lights on the heat sink. I brought the lights from eBay It is 3w 660nm grow led light. I used 10 of them , 5 for each side. I also brought the driver from the same dealer on line. It was cheap enough, but it took about a month to receive them.

Step 5: Soldering the Wires

I connected the lights by series.

Step 6: Lights and Heat Sink With the Driver

Step 7: Fixing the Light Unit to a Piece of Plastic Penal to Secure Their Position

I also used the LED light covers to protect and magnify the LED lights, and they are also from the same dealer online. Due to the lack of professional tools, the wholes in the panel were bigger than it needed to be. I used some play modeling crayon to fill the difference. I highly recommend anyone who wants to build this part to use professional tools, since the modeling crayon is conductive for electricity

Step 8: Building the Plastic Box and Pluming

Most of this step are made in Lowes I brought the plastic panel at the store then let them cut it to the shape I needed. The dimensions are following: 12"*8.5" *2 4"*8.5" *2 4"*12"*2 It should be in 6 pieces of panel, but the big panel was not big enough for all I wanted. I left the top open, which means I only got 5 pieces back. I used 100% silicon glue to put them them together. Three 1" wholes were drilled, one on the bottom, two on each of the sides. (Shown in the pictures) 3/4 PVC connected the drains and top part of plumbing.

Step 9: Connect the Cup Fan and the Light Unit to the Box.

CPU fans were attached to the light unit, then I attached the whole thing to the box by plastic screws.

Step 10: Prepare the Scrubber

Plastic net was found in Hobby Lobby store. I cut the net into 7"*10" dimensions, then used a steak knife to scratch the surface. A piece of black tube and zip tie was used to fix the net in position.

Step 11: Prepare the Waterfall Pipe and Operation

A pice of 12" PVC pipe was cut. I cut the middle of the pipe so the water can flow down. I inserted the plastic net into the pipe then got ready for test. For the pluming part, I used soft clear tubing, since it's much cheaper than PVC connections. I also used the pump maxjet 1200 and a 3/4 water valve on the system.

Step 12: On the Tank!

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    9 Discussions


    3 years ago

    Here is a nice diy simple upflow version you can do next time:


    3 years ago

    How is your scrubber doing? There are many new designs available now, like upflows which stay below the water level.

    1 reply

    Reply 3 years ago

    Thank you for your reply. I was out of country for a while, since I built my scrubber couple years ago. The tank and the system were sold to a local hobbyist before I left. It was hard to let them go.

    My hobby has been downgraded to a 15G fresh water community tank, since I came back to the States, and I have switched my filtration system to a aquaponics system.

    It was low maintenance as well. I might post another instructable in the future.

    I am still interesting in building another scrubber when I have a saltwater set up.


    I've built several algae scrubbers with many variations on the waterfall design. Some worked better than others. A few things about this build--

    You should use thermal epoxy like Arctic Silver instead of regular epoxy to attach the LEDs. Regular epoxy won't transmit the heat away from the LED to the heatsink as well as the special thermal epoxy, and they will run hot and die faster.

    With a large enough heat sink and the right epoxy, you will probably find that the CPU fans are not needed, which would simplify the build.

    For LED coverage, figure each LED covers a 2"x2" area, so here probably should be three times as many LEDs for this size screen.

    No optics are needed since the LEDs are close to the screen. Optics may concentrate the light too much and cause the algae to "burn"

    That screen looks quite large for the size tank unless you are feeding an exceptional amount of food.

    High flow is critical for a waterfall scrubber. The MJ1200 is probably under sized for a 10" screen. Flow through the pipe should be minimum 35 gallons for each inch of screen. The MJ may say it puts out this much, but probably not with plumbing losses.

    For a reference design, look at the "professionally" built scrubbers from Turbo's Aquatics. He's just a DIY guy who built a really nice one, then friends started asking him to build them one, etc.

    To correct the issues and give a better chance of success with this scrubber, I would trim the screen to 6" wide x 7" long, and cut a new pipe with a 6" slot to match. That should still give plenty of scrubbing power, while "right sizing" the screen to the LED power and layout and the size of the pump.

    As for the comment about still needing water changes, that may or may not be true depending on how well the scrubber is performing balanced against the food input into the system. With a highly performing scrubber, the bigger problem might be not having enough nitrates left for the plants.

    yseng huat

    5 years ago on Introduction

    A cycled tank with fully matured biofiltration eliminate nitrites and ammonia, producing nitrates. An algae scrubber should remove nitrates and phosphate if it is working well. Giving lazy fishkeepers an excuse not a water change regularly :)

    How well are ur plants doing with an algae scrubber running? Are there still algae left in ur tank?


    6 years ago

    Thank you for the comment. There are too many variables for this hobby. You can adjust many parameters to reach your goal, which keeps the fish alive and happy. This project is one of the solutions. I used to own a saltwater aggressive FOWLR 75G, but the regular method of water changing almost dug a whole in my banking account. I just hope to find an affordable way to enjoy my hobby. Have a nice day.


    6 years ago on Introduction

    Interesting build, but you can change lighting power and time or nutrient levels and your algae problem will stop. Also water changes are not just for algae, they are to remove excess ammonia, nitrites and nitrates. If you stop water changes you will be slowly poisoning your fish. If you can clean your algae scrubber every week, you can do a 20% water change every week...


    6 years ago

    Sounds like an good idea:)