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http://www.youtube.com/watch?v=LJxzeAgOS_M
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Great Barrier Reef Aquarium
Many people who have not built a scrubber properly (after August 1988) often say how the Great Barrier Reef aquarium was a scrubber "failure" because the corals did poorly. Apparently these people have not done much reading. In the early days of that aquarium, the scrubber was doing it's job great:
1988:
Nutrient Cycling In The Great Barrier Reef Aquarium
http://www.reefbase.org/download/download.aspx?type=10&docid=10506
"The Reef Tank represents the first application of algal scrubber technology to large volume aquarium systems. Aquaria using conventional water purification methods (e.g. bacterial filters) generally have nutrient levels in parts per million, while algal scrubbers have maintained parts per billion concentrations [much lower], despite heavy biological loading in the Reef Tank. The success of the algal scrubbers in maintaining suitable water quality for a coral reef was demonstrated in the observed spawning of scleractinian corals and many other tank inhabitants."
But did you know that they did not add calcium? That's right, in 1988 they did not know that calcium needed to be added to a reef tank. Even five years after that, the Pittsburgh Zoo was just starting to test a "mesocosm" scrubber reef tank to see if calcium levels would drop:
1993:
An Introduction to the Biogeochemical Cycling of Calcium and Substitutive Strontium in Living Coral Reef Mesocosms
http://onlinelibrary.wiley.com/doi/10.1002/zoo.1430120505/abstract
"It was hypothesized that Ca2+ and the substitutive elements Sr2+ and Mg2+ might [!] have reduced concentrations in a coral reef microcosm due to continuous reuse of the same seawater as a consequence of the recycling process inherent in the coral reef mesocosm."
"The scleractinians (Montastrea, Madracis, Porites, Diploria, and Acropora) and calcareous alga (Halimeda and others) present in the coral reef mesocosm are the most likely organisms responsible for the significant reduction in concentration of the Ca2+ and Sr2+ cations."
"Ca is not normally a biolimiting element, and strontium is never a biolimiting element; HCO3 [alk] can be. It appears that, because of a minor [!] limitation in the design parameters of the mesocosm, these elements and compounds may have become limiting factors. [...] It is surprising that the organisms could deplete the thousands of gallons of seawater (three to six thousand) of these elements even within two or more years [!!].
"The calcification processes are little understood."
So then in the late 90's, the Barrier Reef aquarium start using up it's supply of calcium, and the folks there said "the corals grew poorly". Really. No calcium, and the corals grew poorly. So they "removed the scrubbers" and "experimented with the addition of calcium" sometime after 1998. Then in 2004 it "definitely improved a lot". Really.
Low-light Scrubbers
Here is something new, different, and untested. I have not built one yet, but it should work for either SW or FW if the size and flow are correct. It is a vertical scrubber that you hang on the wall, and it requires NO electricity. It is a "low-light" scrubber:
I got the idea when reading a study about algae growth in freshwater streams:
"Algal Response to Nutrient Enrichment In Forested Oligotrophic Streams". Journal of Phycology, June 2008. http://www3.interscience.wiley.com/journal/120083425/abstract
"Algae inhabiting forested streams have the capacity to acclimate to low light intensity. These light conditions affect their photosynthetic efficiency, but do not impair growth rates, in particular, in the case of thin diatom-dominated communities."
In other words, they don't filter as much per square inch (or per square cm) of area, but they do operate on very low light. Apparently it is mostly diatoms that grow in these low-light conditions.
The advantage of a scrubber like this should be obvious: It requires no electricity to power the screen. It still requires a pump, however, since the top of the scrubber would (probably) be high above the top of the tank. The scrubber is designed to operate on the light already available in the room, which would vary greatly depending on how strong the light bulbs are in the room, and how much sunlight comes in through the windows. The more average light the room has, the smaller the scrubber can be. The less light, the bigger it needs to be. Basically, the scrubber uses more area to make up for less light. And since the light is so low, the type of algae that is able to survive is (apparently) mostly diatoms.
Just as with regular scrubbers, the wider the unit it, the more flow is required. So in the spirit of keeping it from consuming too much electricty, a smaller pump could be used if the unit were narrow and tall. But the bottom of the unit will need to drain into either the tank or the sump, so there will be a limit to how low the bottom can be. And the limit to the top will be the ceiling. A tradeoff will need to be made, maybe so that it looks like a vertical picture on the wall. Fortunately the flow does not need to be as much as a regular scrubber, since it is one-sided only.
It will have to be experimented with to see if a clear cover is needed to stop any water dropletts from splashing out. Many people have decorative waterfalls of the same size as these, and they have no cover on them, so maybe water dropletts getting on the floor will not happen. Evaporation would be high though, and this might be reason enough to consider a clear cover.
Cleaning could (apparently) be done by having a removeable screen or porous sheet, just like a regular scrubber has. It would be big though, and would drip as you took it out. Also it probably would not fit into a sink, and so would need a bathtub or shower (or outside) for cleaning. A possible fix for this might be a very flexibe woven plastic mesh, which you could fold up like a towell and easily clean in a sink. A material like this might not lay down flat when it's in the scrubber, however.
This type of scrubber would be easiest to try for somebody with a cement floor, lots of wall space, open widows or skylights, a low sump, high ceilings, and a big sink or patio for cleaning. I have no idea of the size required for the unit.
New Feeding Guideline:
Each cube of frozen food you feed per day needs 12 square inches of screen, with a light on both sides totalling 12 watts. Thus a nano that is fed one cube a day would need a screen 3 X 4 inches with a 6 watt bulb on each side. A larger tank that is fed 10 cubes a day would need a screen 10 X 12 inches with 60 watts of light on each side.
Well it took a while to get time to take more pics, but here are the updated ones of my 100 gallon tank. The main thing to mention is that this tank is not for showing... it is for experimenting. Details are at the end of this post. There have been no waterchanges since August 2008. The only dosings are Mrs. Wages Pickling Lime in the top-off (for Cal and Alk), Seachem Reef Advantage mag, and Seachem Reef Advantage strontium. Feeding is 48 ml of skimmate... I mean... blended oysters, per day, 20 square inches of nori per day, and one silverside per week (for the eel). There are no mechanical filters, no chemical filters, and no sand. The only filters are the live rock (now 5 years old), and the algae in the scrubbers. The lighting is 2 X 150 watt halides, and one 96 watt actinic. The tank is 30 inches tall. Tests are Nitrate and Phosphate = 0 (Salifert), pH = 8.3 to 8.6, and the water is contantly filled with food particles: 

High-Res: http://www.radio-media.com/fish/Oct2010Tank.jpg
Videos:
Whole Tank: http://www.youtube.com/watch?v=xUl8FIQAxr0
Tank Right to Left: http://www.youtube.com/watch?v=58pOisX2vSs
Eel Eating: http://www.youtube.com/watch?v=kDZtHf-xXCc
Flower Pot: http://www.youtube.com/watch?v=MMdllQSKU2c
Frag Tray: http://www.youtube.com/watch?v=AtvF0ZbVX7w
Liquid Feeder: http://www.youtube.com/watch?v=iOIx09XWYCo
Tube Anemone: http://www.youtube.com/watch?v=p7TnVm19td4
Here were the main experiments:
Iron Overdosing: I tried adding an iron supplement for many years, but never saw any affect. I always followed the instructions, such as Kent's Iron+Manganese "Add two teaspoons per 100 gal, per week". It had no visible effect. But after I started to read the literature about algae and iron, and after I realized that I now have much more algae in my system that the average tank does, I went out on a limb and poured in 8 ounces of Kent's. This is 24 times the recommended dosage for 100 gallons. But I reasoned that it's not the gallons that matter, it's the amount of algae. And it worked. The algae in the scrubber, that previously was yellow and hard (due to lack of iron), turned solid green and fluffy. Growth was much faster that week too.
So if more was better, much more should be much better. So I poured in a HALF GALLON of the Kent's. This is 225 times the recommended dosage, and over 9 times more than what I put in before. This was the biggest mistake I've made yet on this tank (coral-wise). Within a few hours, both of the bubble corals shrank up to nothing, and started letting pieces go. The next day, my 3 year old 5" litho was half gone. And by the end of the week about 30 of my 60 corals were completely wiped out. Iron was even beginning to deposit on the inside of the tubing that feeds the scrubbers. Well, I never did a waterchange, and things have gone back to normal, but now I know the power and the problems of adding iron. The more algae you have in a system, the more iron it can use; but don't add too much. How much is too much? The green soft corals (like a green bubble) seem to be affected first, so watch those.
Over Feeding: When my scrubber (only one unit at the time) was basically not filtering at all (before I knew about pumps clogging, and lights getting weaker), I increased feeding to 128 ml of skimmate... I mean blended oysters... per day, along with 5 frozen cubes per day, and one silverside per day. No waterchanges of course. So with this high level of import, and with almost no export, nuisance algae began to explode in the tank. I must say, the few SPS I had really grew at that time. The over feeding made up for the small 150 watt halides in a 30 inch tall tank.
Non Feeding: After realizing the non-flow in the scrubber (due to the clogged pump), and the worn out lights in the scrubber (should have been replaced 9 months earlier), I got the export back into operation. But to speed up the removal of the nuisance algae in the display, I stopped all feeding for 2 months. No blended oysters, no nori, no cubes, nothing. Only one silverside for the eel, but only every 2 weeks. Well, another big lesson learned: If corals have been growing based on high amounts of food in the water, they cannot survive on less. In other words, if the food in the water was always low, the corals would not have developed a need for food. But since they were fed large amounts of food for a while, they grew and needed those large amounts at all times. When the feeding was stopped, I lost about 4 corals in the first 4 weeks, and another 10 corals in the next 4 weeks.
Love the flower pot and the color of your Yuma ... ![]()
Thanks... I llike those too.
SM,
Ok, so I'd like to change my screen out due to the poor fasteneing system i used on my initial design causing minor spray issues.
What's the best way to do this? I don't want to start all voer with no filtration of course, how do I seed that new screen in?
Cut the old screen vertically in half, and replace half at a time with a new one.
I think I went almost 8 months without a water change when I ran my scrubber.They work good.
Im having Nitrate troubles these days.Everything else is perfect..as in undetectable. Scrubbers will work of nitrates alone correct? I think I will start one up again.
Hello Santa Monica,
I am very interested in your algae filtration method. I plan to use it on my new tank. I wonder if you could answer a few questions.
In order to achieve the 3-D algae effect, what do you feel is the optimum distance from the screen to the sides?
I am trying to use the absolute least amount of electricity for my tank. Do you know which T5 lamps grow the algae fastest? I plan on putting the T5 in a reflector and placing the reflector directly against each side. The lamps will be 24 inches wide and so the screen will be about 24 inches wide, but with a single lamp on each side of the screen what do you think the maximum height of the screen could be?
Could you give me a link that shows the best way to fasten the screen to the pipe and also to get the water to flow down the screen?
What photoperiod do you use? I saw a study on Cheato algae that showed maximum growth in the first six hours of illumination. After that the growth fell off dramatically. I wonder if the same holds true for most marine algae. So I am considering six hours on and six hours off as a starting point.
Any tips or help you could give me would be greatly appreciated.
I used to live in Taft. Every now and then we would drive our motorcycles through the coastal mountains and end up in Santa Monica. What a beautiful ride that was. Especially in the spring. I hope Santa Monica is still half as pretty as it used to be way back then.
Joe