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Thread: The Super Guide to Algae Turf Scrubbers

  1. #1
    Join Date
    Oct 2008
    Santa Monica, CA, USA

    The Super Guide to Algae Turf Scrubbers

    The Super Guide to Algae Turf Scrubbers

    Part 1

    Filtering your tank by using "algae to fight algae" has been gaining in popularity in the last few years. We are biased about this, because we invented the waterfall and upflow designs that everyone uses now, but nevertheless we wanted to make this in-depth series about everything, including:

    ∑ History of scrubbers
    ∑ DIY topics
    ∑ Commercial models
    ∑ Comparison to other filters
    ∑ Usage with other filters
    ∑ Sizing
    ∑ Lighting
    ∑ Water flow
    ∑ Operation
    ∑ Fresh vs. Saltwater
    ∑ Effects on animals
    ∑ Troubleshooting
    ∑ Dosing
    ∑ Types of algae
    ∑ Results in tank
    ∑ Uses of algae
    ∑ Safety

    First, the origin of scrubbers should be mentioned. It was Dr. Walter Adey of the Smithsonian Institution in the USA who really got the scrubber concept going in the 1970's, when he was investigating nutrients and corallines on reefs:

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    His nutrient measurements confirmed what other researchers had found, which is that nutrients basically "stay on the reef" and do not flow out into the ocean, even though the water itself flows out into the ocean. It was already known back then that reefs are both generators and consumers of nutrients, consuming any nutrients as soon as they were available (thus making reef water "nutrient poor"), but he wanted to investigate further into who generated and consumed what, and by how much. He started publishing many reef nutrient studies, and came out with the first edition (now in third edition) of his Dynamic Aquaria book which describes in great detail about nutrient flow in reefs, corals, algae and animals:

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    Adey's big contribution to the aquarium community was in the separation of the nutrient generators from the nutrient consumers. The generators are the animals, micro creatures, and bacteria that all generate ammonia, whereas the consumers are the algae which consume this ammonia. On reefs this is all intermixed, and it keeps nutrients inside the reef, but he separated out the algae and created a device which mimics the environment where the most biomass of algae grew the fastest: where waves crash down on rocks. As soon as you scraped algae off of these rocks, it could be fully regrown in just 24 hours, and that's even while teams of herbivores were eating it. This could be a 100x increase in biomass in 24 hours, which absorbs a tremendous amount of nutrients from the water.

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    His device in 1980 used a dumping bucket to pour water onto a very shallow screen, and thus made a bubbling turbulent air/water interface that grew a lot of biomass of algae fast, and he called this device a "turf scrubber" because it grew a turf algae and it scrubbed (removed) nutrients from the water. By separating the nutrient producers from the nutrient consumers, the conditions for operation of the consumers can be controlled and optimized without changing the conditions for the rest of the reef (aquarium) itself.

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    Adey licensed the design to someone to have some small models made, but nobody ever really sold many of these dumping bucket designs because they were so big, complex, splashy and noisy, and also they were just 1-sided (top side) only which grows less. Also, Adey never had any interest in making or selling them himself, so they disappeared.
    Later in the 1990's a few people made and sold the simple horizontal river design, like the Aquaricare scrubber which had little baffles to stir up the water and create a more turbulent air/water interface (the light on top is removed for the photo). But it too was large, splashy, hazardous (used high voltage T5 bulbs and wiring), and was also just 1-sided (top side) which meant it had to be larger to make up for less dense growth.

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    Then in the 2000's the last "different" version of an algae scrubber was introduced, the Eco-Wheel. This was a giant, expensive, complex rotating machine that did work, but no known installation pictures have been found; just this small photo from a sales ad:

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    And so, up until 2007 the basic algae scrubber designs were the dump bucket, horizontal river, and rotating wheel. And none were really being sold, so nobody knew about them.
    Then came "SantaMonica" (us!) on the forums in 2007, with the first waterfall style scrubber. The thinking was that there must be an easier way to get a turbulent air/water interface on a screen than using a bucket, a wheel, or a river. Let gravity do the work straight down! And a waterfall on a screen could have lights and growth on both sides, so it would grow more and could be half the size. This first waterfall was put into a bucket on a sink in the office, complete with dangerous CFL bulbs that got shorted by salt spray. This was all posted on various forums as "Waterfall Turf Algea Filter: CHEAP and EASY to build" if you want to read it.

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    It grew great, and brought nutrients down to zero with no water changes. But in order to get a waterfall in to our sump area it would have to be low-profile, so a custom acrylic box was made and the SantaMonica100 was born (100 was for 100 gallons)..

    This was the first model to sell any real amounts. But it had flaws which caused it to be left behind in favor of our modern versions. First, it could not reliably be mounted anywhere but over a sump, because a clogged drain would cause an overflow onto the floor, or a clogged slot would cause water shooting out the top, even with a lid. Second, the cleaning/harvesting process was very involved, requiring water shutoff and disassembly of some plumbing or even taking the whole scrubber out. Third, the acrylic was fragile and easily cracked, especially after many heating/cooling cycles. And lastly, the high voltage 240/120 volt metal-case lights were dangerous for non-DIY users who just wanted a safe product. The lights would slowly corrode in the salty environment, and eventually short out.
    And so there you have it; the evolution of the algae turf scrubber from the 1970's to today. We'll get into many other topics, but for now will just link to one of our smaller modern models, the HOG1, which is a great "starter" scrubber.


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  2. #2
    Join Date
    Oct 2008
    Santa Monica, CA, USA
    The Super Guide to Algae Turf Scrubbers: Part 2

    By Santa Monica Filtration

    Now letís get into the first question that most aquarium folks have about scrubbers: Should you buy or build? Before the year 2010 there were not really any options to buy, but now you can buy tiny to medium size scrubbers in the upflow style, or medium to large sizes in the waterfall styles. And for building DIY, discussion forums now have examples of every attempted scrubber ever thought of, complete with growth examples and nutrient measurements over time. There are some really amazing builds that have been done. We wonít get into DIY plans here though because there are so many available elsewhere, such as our AlgaeScrubber.Net forum that goes back to the very first builds in the year 2008.

    An algae scrubber can be made DIY fairly easily if you are good with building. The typical materials of pvc pipe, acrylic sheet, glue, airline, etc are needed, just as if you are building a DIY reactor, overflow, or sump. One difference with scrubbers however, which makes them a bit more difficult, is the lighting thatís needed for the growth. Not only are you now dealing with electricity, but unlike DIY display lights which are above the tank in a dry air environment that you rarely touch, the lighting for a scrubber is in a humid or wet environment (or even underwater) that you touch daily, with wet algae dropping on top of it, all while possibly standing on a wet floor (maybe even with bare feet). So donít make a complex algae scrubber your first-ever DIY project.

    Some advantages of buying a scrubber are that you obviously donít need the time or space to build one. But other reasons are that itís hard to DIY some types of scrubber designs, even if you are good with DIY. Things like underwater lights for upflow scrubbers, or gravel-epoxy surfaces for algal attachment, or the long slot in a waterfall pipe, takes a few tries to get it right (meaning your first try will probably not work).

    Buying a pre-built unit, however, is limited to what is for sale. Currently the only models available are waterfalls (which we invented in 2008 and are now made by us and others) and upflows (only made by us), and these are in certain sizes only. There are a very few number of horizontal river models, but these are from China, are tiny, and are without any lights. And there are no dumping bucket designs available at all, probably because of their complexity.

    The big advantage of DIY is of course money; most $300 USD commercial models can be DIYíd in a week for $60 in parts, and most of this is probably for the lights. But DIY also lets you choose the exact style, size, and layout you want to fit into your exact space. If you need a very large model, such as for small exhibits at public aquariums, you will have to DIY.

    DIY waterfall styles are generally going to need some acrylic or plastic gluing, unless you can find the proper size plastic box to start with. Cutting the slot in the waterfall pipe is the hardest part, and although it can be done with a Dremel moto-tool cutoff wheel, most people end up doing it over again with a table saw, router, or other shop equipment. The lights are easy however; usually the low cost Chinese plant-grow lights can be used from Ebay, as long as you follow the safety steps such as shown in LEDsafety.org properly. Most DIY folks can do the pvc pipes, so thatís not a problem. Waterfalls are not really suitable for freshwater, however, because the growth gets long and clogs drains and pumps. Also, waterfalls work best when placed over a sump; not externally on their own, because they can overflow, leak, and also drip from the waterfall pipe.

    DIY bubbling upflow styles can be the easiest, if they are similar to the Hang-On-Glassģ styles that we make. These styles need no acrylic gluing or pvc pipe, and the LED lights just stick to a plastic cover on the outside of the sump or tank wall using magnets or suction cups. And the airline tubing for the bubbles is as easy as a goldfish tank. Cheap LED lights and a power supply from Ebay will do because they stay dry and are low voltage (no 240/120 volts at the light). These designs might be suitable for first DIY projects if you can get help with the lights, and are great for freshwater too because the long growth is kept mostly inside the growth compartment. Lastly, they canít overflow, leak, or drip because they are already underwater.

    DIY horizontal rivers are relatively easy to build; at least the river water part is. But again, the lighting can be a challenge over the long narrow pathway. One workaround for this is to put it under your display lights, but thatís just too cumbersome and unsightly for most people. And if put over a sump, these designs tend to cover the top of the sump like a lid, so you canít get to anything.

    If you have multiple tanks, a good bit of advice is to try a scrubber first on the smallest one, especially if itís freshwater, because that way you can get a feel for placement, lighting, cleaning, sounds, etc. before working up to a bigger one. Meanwhile if you want to take a look at modern scrubbers, here is our SURF2 floating model, shown floating on a saltwater reef pond:


    Happy Scrubbing!

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  3. #3
    Join Date
    Oct 2008
    Santa Monica, CA, USA
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    The Super Guide to Algae Turf Scrubbers: Part 3

    By Santa Monica Filtration

    Now letís talk about the difference between fresh and saltwater algae scrubbers. They are different designs because the algal growth you get in each are different, and so the layout of the scrubbers needs to be able to handle this. Freshwater growth tends to be mostly Spirogyra or Cladophora species, which are very long (one meter) and very thin, like a string or thread:

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    This super long growth means two things: First, itís going to try to flow with the water flow, which can be a very long pathway. And second, if the growth lets go, there is going to be long strings of growth finding their way through the aquarium pipes, pumps, etc. Since many freshwater people put the scrubber in their display (because they donít have a sump) this long growth can get all over.

    A plus for freshwater is that many of the fish that people keep (gupplies, goldfish, plecoís, etc) love to eat this algae, so it can be an endless source of fresh free food. Matter of fact itís relatively easy to have a freshwater tank that needs no outside food or waterchanges at all, and yet still has low nitrate. And the fish get to eat what they love the most.

    Long freshwater growth is fine if your scrubber and installation are set up for it. Generally you donít want a waterfall style for freshwater because the long growth flows right down the drain with the water flow, and can extend for a meter past that:

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    If itís a waterfall in a sump, this growth will get caught up (or will clog) the return pump. And you canít really put a waterfall over a display, so it must go in the sump. Thus waterfall designs are not recommended for freshwater. Upflow designs however are particularly suited to freshwater:

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    o Upflows are easy to DIY, by using a common air pump which many people already use for freshwater.
    o Freshwater people usually want bubbles.
    o Many freshwater tanks have no sumps, which is no problem for upflows because upflows can go into the display.
    o Since filter units in freshwater usually go in the display, the fish can pull the algae out and eat it.
    o The long growth is circulated around (and held) inside the upflow container, keeping most of the growth from clogging other filters or pumps.

    Now letís look at saltwater. The big difference with growth in saltwater is that it grows much coarser and thicker strands (Ulva species, etc) which tend to be curly but also much less long than freshwater. So you no longer have to deal with long growth that grows out of the filter, and this means that any version of a scrubber will work: upflow, waterfall, or horizontal river. But with saltwater you do have to deal with thick growth that blocks light.

    The concept of blocked light is important because algae will die when light blockage occurs. And dead algae cannot hold on, so it washes away, and there goes your filter. Itís ironic: Thicker growth seems great, but it blocks light, which kills the growth. Dead growth is brown like hay, and can give water a yellowish look. So what to do?

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    Well fortunately the growth does not die right away; it takes a few days once the light has been blocked. So as long as you clean/harvest before the ďrootsĒ die and let go, you are good (algae do not really have roots but do have holdfasts which grab solid surfaces). A few tricks will let the growth go more days before die-off happens. You might think you could just reduce the hours of light so it does not grow thick so quickly, but this reduces filtering too and thus defeats the purpose of growing fast, not to mention it gives more hours of darkness which does not help the roots. So the trick is to grow fast but not shade the roots too soon. Here are some things to look for or try:

    2-SIDED: A waterfall or upflow screen should be illuminated on both sides, so the roots that are grabbing the screen get light from both sides. This will let the growth go several more days before the roots get zero light.

    STRINGS: Adding strings to a screen or a solid surface lets the growth grow away from the screen or surface, thus getting the roots out of the darkness. Strings by their nature are already 2-sided.

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    GROWTH RINGS: Usually the middle of a screen is where the growth is the thickest and the die-off occurs first. By using very strong light in the middle of the screen, this area can be kept un-grown until an outer ring grows first, thus keeping the middle alive longer. The term for this is ďphotoinhibitionĒ.

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    EATING: By letting your animals eat some of the growth, the time for the growth to get too thick will be lengthened, or maybe, the growth will never get too thick.

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    ALTERNATE CLEANINGS: Instead of letting the growth go a full 7 to 14 days before cleaning, you can clean half of it every 3 to 7 days. Since you are cleaning / brushing / scraping right down the middle of the growth surface, this opens up the middle to more light.

    SPLIT SCREENS: A more elegant way of doing alternate cleanings is to divide the growth surface in half, and clean each at alternate times. A waterfall screen is easily cut vertically for this.

    MULTIPLE UNITS: The ďmostĒ elegant way of achieving alternate cleanings is to have multiple scrubber units. This achieves the same growth time for each growth area as above, but you do not have to deal with taking/leaving part of the growth behind, and you also do not tear growth in half which can put little bits of growth into the water. It also is the most expensive way.

    Remember, the above information is for after a scrubber has been growing, or after you get through a slime stage. No scrubber will look or perform like this when brand new. For an example of a modern freshwater scrubber, here is a high power HOG2x with extra light for high nitrate water:


    Happy Scrubbing!


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