Tank Gadget The Home of the Aquarist Geek

I have an algae problem like nothing I have seen anywhere else, except in that fish store that is maintained by teenagers who would rather be out hangin’ with their homies than looking after all the dead fish in the tanks.

In the sea, if you wander down to the shoreline, you will see 1 of our most used tools at work. On some shorelines, you will see a buildup of froth when the waves come crashing in. what does it remind you of? Right! Your skimmer. the froth is the skimmate of the sea and it builds up and is filtered out in the sand and on the rocks.

Another tool you will see at work is an algae scrubber. Have a look at the rough rocks with algae growing on them. Usually if it is there it will be in abundance. This is where the ocean has a concentration of nitrates/phosphates and what-have-you that encourages the algae to collect and thrive on the rocks. An algae scrubber offers the same thing, but on a much smaller scale. The purpose is to make the algae want to grow somewhere else instead of inside your fish tank.

Scrubber Image courtesy of Algaescrubber.net. Algae on rocks from Sandiegofun.net

The basic design principal is to take tank water and run it over a textured surface. The algae particles in the water column will adhere to the surface and the algae will grow, given enough light. Once the algae grows, it will continue to do so. The algae growing on this surface will be more inviting than growing in your aquarium. Why? It will be brighter, nutrients will be more concentrated and the flow of the water will be more vigorous.

The most important feature of the scrubber is the lighting. the brighter the better, and to make it more efficient, have the algae grow on both sides of the surface. Use 2 lights!

The components usually consist of a pump, some PVC tubing and a screen. the screen is suspended from a length of PVC with holes drilled or cut into it. The water is pumped through the PVC tube and allowed to flow down over the screen. More complex designs can be done to improve effectiveness, like having multiple screens and lights, enclosing the whole thing into its own box or tank, making it almost horizontal instead of the usual vertical, and the list goes on. See this link for a huge list of design ideas.

Cost of a scrubber is very cheap. you can probably assemble all the supplies for under $30, including lights. Many simply use a standard socket with a curly compact fluorescent bulb backed by some makeshift reflector to direct as much light to the surface of the scrubber as possible.

Besides lighting, the next most important thing with an algae scrubber is keeping it clear of excess algae. You don’t want to completely clean it. You want it to grow a nice base, or as is commonly called, the “turf” that stays attached to the screen. This gives algae the reason to grow there. Once a week the scrubber needs to be cleared of the excess. This is done because as the algae grows, it gets thicker and blocks out any light to the algae that is growing deeper on the surface causing it to die inside. Death of algae can lead to leaching out of the stuff you are trying to filter out. Nitrate and phosphate levels will rise, water will begin to discolor and that smell, you know the one, will start to emanate from the scrubber. The cleaning is the demanding part of the scrubber but this can be done in 5 minutes so it is not a time-sink like a water change.

So there you have it. A properly and effectively run algae scrubber can take over the job of a skimmer. Many people run both, but in many cases the skimmer has been removed as the scrubber filters out most of that bad stuff and more effectively.

Sadly there are no manufacturers of algae scrubbers, so we are left to our own DIY projects. I will be building one soon to battle my algae problem and will post about it here. If you have a scrubber running, please let us know how you like it, we’d love to get pics too!