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(UAS) DIY Freshwater Up-flow Algae Scrubber #algaescrubber

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My Current Cichlid Tank

My 29-gallon cichlid tank with 6 mbuna's and 1 small catfish

My 29-gallon cichlid tank with 6 mbuna's and 1 small catfish

What is an Algae Scrubber?

For a basic answer, my research has led me personally to discover that an algae scrubber is an aquarium filter that works on both freshwater and saltwater aquariums and it works in nano tanks as well as large aquariums! It utilizes light, water, oxygen, and tank nutrients for it to work which in turn allows algae to grow in a small area within your tank, above your tank, or inside a sump below your tank, and it does so in a controlled manner. Now, I didn't attend the York Academy of Sciences, or any other school that goes into depth of what happens on a chemical level. All I know is it works. The algae absorbs any undesirable nutrients in the water, it helps to keep nitrates, nitrites and p04 (phosphates) to near or at zero, and it also keeps other competeing algae from growing in other areas of your aquarium, dt or display tank, keeping it looking clean and healthy. Because trust me algae in aquariums, such as brown algae and hair algae, are a nuisance and they are unsightly. Oftentimes, this type of tank filtration system, an algae turf scrubber, is all that is needed to run an aquarium. However, the more that is learned and as more experiments are carried out, things may slightly change. I will explain more later!

Waterfall Algae Scrubbers

Waterfall Algae Scrubber

There are a numerous types of algae scrubbers used by individuals, but the one that is extremely popular and works real well is a waterfall scrubber. This type of algae turf scrubber (ATS), takes water from the aquarium and flows it downward over a rigid screen and back into the tank. If you have adequate intense lighting and air, in time, algae will begin to grow on the screen. With the correct amount of water flow and nutrients, it doesn't take long for this to happen and when it does weekly cleaning of the screen is necessary to keep the process going.

Up-flow Algae Scrubber

Up-flow Algae Scrubber

Another type of scrubber that has caught a lot of attention lately is an up-flow algae scrubber (UAS). This scrubber is very similar to a waterfall type except this time the rigid screen is immersed in the water with the same high intensity lights as the waterfall design. But instead of water flowing over the screen, air bubbles are forced to flow up from the bottom of the screen. The air bubbles envelope the screen with nutrients that you want removed from the water and in time algae will begin to attach itself to the screen, absorbing those undesirable chemicals as it grows. Kinda cool, don't you think! It ought to because it is very similar to what takes place in the oceans, lakes, rivers, and streams. You can't go wrong mimicking mother nature!

Other Algae Scrubber Designs

  • CDMills Designs: A New Unique Algae Scrubber Design
    We have seen horizontal scrubbers, waterfall scrubbers, and upflow scrubbers. My new design is an in-flow scrubber that is meant to go under the water in a sump with the light in the middle for 360 degree coverage.

My DIY Freshwater Algae Scrubber Project and Ongoing Experiment

Both the waterfall and UAS algae scrubber filters are extremely intriguing to me. And I may end up using a version of both when I build my new tank. But for now, I have a 29-gallon freshwater Cichlid tank that I want to try the UAS filter on. If anyone else is interested in building a UAS diy algae scrubber, you can check out the forum over at and click on the Upflow Algae Scrubber(UAS) link, to learn how to properly size your screen, what type of bubble flow rate you will need, and what kind and how much lighting is necessary to get your filter up and thriving. A couple of guys on that sight are algae scrubber wizards. Check out the Santa Monica algae scrubber guru and his algae scrubber designs.

My Step-by-Step Freshwater Upflow Algae Scrubber Build

The Screen Size

OK, back to my current do-it-yourself project. (You can easily see my build by viewing the picture slideshow) My screen size is 3"x4" (12 square inches) which is roughly based on my feeding of 1 cube of food daily. The type of screen size guideline that is currently being used is this: screen size should be based on how much you are feeding your tank. But, I would recommend that you keep yourself updated on this because things change, and I say that because it can happen.

***I will also be providing updates at the end of this hub on a regular basis to show the progress of growth on my upflow algae scrubber as well as any changes and upgrades I make***

Sidethought: I have a theory about this guideline, and it is only a theory and it would only apply to freshwater tanks (it could apply also to a fish only saltwater tank, I suppose). My thinking is, the size of the screen should be based on the average size of your fish (adult size). For example, I have 6 mbuna cichlids and one catfish. I have had them for over a year and their average length has grown to 2-inches. So if you take the average size times the amount of fish of have, you will get your average screen size in inches. Thus, in my example, you would have to have a screen that would be 14 square inches, which would account for a little more growth and overfeeding. I don't know, it's just a theory but it ends up close to the current recommended screen size guideline based on feeding. But as it is, I stuck with the current guidelines for my build. Maybe someone else would like to experiment more with my theory. Say for instance you have 42-inches of fish in your tank. You would need a 42-inch square screen (7"x6"). Any thoughts? Again, it's just a theory!!


The Screen Material

  • The first thing I did is I went to my local all-in-one store (Wal-Mart) and went to the sewing/craft department and found that they sell a 6-pack of Craft Designer screen. I don't remember what I paid for it but it was extremely cheap and I have enough to build lots of scrubbers!

Screen materiel I picked up at Wal-Mart that will become my algae screen

Screen materiel I picked up at Wal-Mart that will become my algae screen

  • The 2nd thing I did was cut my screen. I cut the screen 3-inches wide by 5-inches. I cut it an inch longer because an inch of the screen is going to fit down inside a 1-inch piece of PVC. You will see this later on in the build.
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  • The 3rd thing I did was got out my 2-inch hole saw and removed the drill bit. I used the hole saw blade to rough up the screen material on both sides. This tool works like a charm because of the saw blade teeth. It really cuts into the plastic screen material and this is important because you want the screen to be extremely course so algae will attach itself easily to it. Rough it up good!!! (click on thumbnails to see full size)
  • The reason this is so important is you want the algae to attach itself to the screen. If you leave the algae screen smooth it's a good possibility that the algae will somewhat stick on, but it will probably slide off when it gets to full maturity. You don't want that to happen. So this point can't be stressed enough! Rough up your screen, rough up your screen, rough up your screen!
To house my algae scrubber screen I purchased a 36 oz lock top storage container. You can go with a smaller container or a bigger container if you have a different size screen

To house my algae scrubber screen I purchased a 36 oz lock top storage container. You can go with a smaller container or a bigger container if you have a different size screen

The Algae Scrubber Container

I'm not real good at building stuff out of acrylic (yet) and I wanted to keep this build as cheap as possible so I searched around for a suitable container that could house my algae screen. I wanted it big enough so that if I wanted to expand the screen size I could but I didn't want it so big that it would take up a lot of room in my aquarium. I happened to find a lock top airtight container that was 36 oz. The dimensions of the box is 8"x5.75"x2".

I was also looking for a container that had a top that was slightly inset so I could install suction cups on it so it would end up fitting tightly against the glass inside my tank. The container I found was perfect! I got it at Bed, Bath, and Beyond for $4.99.

This is the PVC that will hold my algae screen. I cut a groove in it using a drill bit and a file to smooth the sides

This is the PVC that will hold my algae screen. I cut a groove in it using a drill bit and a file to smooth the sides

The Algae Screen Holder

  • I don't know what else to call it so I will just call it the 'screen holder'. I made mine out of 3/4" PVC pipe and 3/4" end caps. On one side of the PVC I cut a groove just wide enough to fit the width of my screen. It is approximately 3 1/4" wide. I made the groove twice the size of the screen thickness. The reason I did this is because I wanted the screen to be able to move forward and backward in the water. Another words I wanted it to sway back and forth, much like it would if it was floating in the ocean. I didn't have a table saw to cut the groove so I clamped it between 2 pieces of wood, a line was drawn down the middle, and then I used a 3/16" drill bit with a point on the tip to drill holes down the line. I kept these holes very close and was able to do it because the bit had the pointed tip (and that was the secret, because I could push down hard and set the bit right on the line without it slipping off the PVC). It took some time but I think it turned out OK. When I was done drilling I used a file to smooth out the sides of the groove.
  • After that, I turned the PVC pipe over and made another groove on the opposite side. This is where the water flows up through the holder and then on up through the screen. You could always just put 4 or 5 quarter inch holes instead. That would make it a lot easier, LOL! Lesson learned!
  • Next I drilled 2 small holes from the front of the holder to the back. These small holes hold 2 small zip ties that just slip in but do not get attached. This holds the screen in nicely and it allows me to remove the screen quickly and easily. With a pair of scissors I snipped out 2 small areas of the algae screen so that the zip ties will go through easily. Plus, this will allow up and down play in the screens movement. So now it will not only move forward and backward, it will also bob up and down. (Remember to use very small zip ties, the smallest you can find).
  • If you want, you can loop the zip ties under the PVC and zip them, but this would be a headache each time you have to clean the screen. You would have to cut the zips and then replace them with new ones every time. Too much work! Just keep them full length and push them through. They will stay put.