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Thread: Using Seaweed to get rid of nuisance algae in your aquarium or pond

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    Using Seaweed to get rid of nuisance algae in your aquarium or pond

    Using Seaweed to get rid of nuisance algae in your aquarium or pond, part 1

    One of the neat things about nature is that it's had a long time to figure things out. Especially under water. Here, nature has figured out how to reduce all the "nutrients" to very low values, and also how to feed every aquatic animal (as well as consume half the world's CO2, and produce half the world's oxygen), by just using sunlight. Not bad. Maybe this concept can be used to help your water pets.

    Well of course it can. And it is already doing so, sort of. It's just not being used enough, or even on purpose. It's sort of the difference between a bicycle and a motorcycle, or a snack and a big dinner. Or even knowing you have a dinner in the first place. It's called photosynthesis.

    You have all heard about photosynthesis; it reminds you of trees and science experiments. But how can it help? Well the basics are this: Photosynthesis takes carbon out of carbon dioxide, and uses it to build living things, and it releases oxygen in the process. You've probably also heard that all living things contain carbon; well, that's where the carbon comes from, and photosynthesis is how it got there. The living things that photosynthesis builds generally are plants (on land) and algae (seaweed and phytoplankton) in the water. Then, anything (like you) that eats these plants or seaweeds will get the carbon you need to grow. Oops, there is one more neat thing that photosynthesis does when building these living things: It uses Ammonia, Nitrite, Nitrate, Phosphate, and many metals like Copper and Iron too.

    Sounds like an ideal filter, right? Removes Ammonia, Nitrite, Nitrate, Phosphate, CO2 and metals, and put oxygen into the water. Also sounds like an ecosystem, like the ocean, or lakes, or rivers. Because it is! That's how the oceans, lakes and rivers are naturally filtered!

    So we will be showing you how to build your own DIY versions of these neat filters (for fresh or salt) in the coming posts.
    Last edited by SantaMonica; 08-01-2016 at 11:54 AM.

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    I will be flowing this closely.

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    interesting!

    sounds interesting! looking forward to reading about it

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    Using Seaweed to get rid of nuisance algae in your aquarium or pond, part 2

    So how does photosynthesis "pull" the carbon it needs out of the air or water? Doesn't CO2 or other nutrients just "soak" into things by themselves? For example, doesn't CO2 just soak into trees? Meaning, if you have more trees, won't more CO2 just soak into them? No, not really.

    CO2 and other things do "soak" into water, but the reason that the water does not "fill up" with CO2 is because organisms in the water "pull" and "eat" the CO2. What organisms might these be? Algae, of course. Or more specifically Photo-Auto-Trophs (photoautotrophs), which means they get their food (carbon) all by themselves (auto), without needing to eat other animals, and they do this using sunlight (photo). In the open ocean and open lakes, all this is done by free-floating algae (phyto plankton), but as you the get to shallower areas of the reefs and lake shores (and in streams and shallow rivers), it is done by benthic (attached) algae on the bottom surfaces. We will be calling all attached algae "seaweed", even if it's in freshwater lakes, because saying "lakeweed" is a bit odd.

    The faster that carbon is taken out of the water by the seaweed on the bottom surfaces, the faster CO2 can continue to absorb into the water at the water's surface. This is an important idea to understand; it forms a CO2 "gradient". This idea is easier to explain by thinking about an oven: Standing far away from an oven, you might barely feel the heat, but as you move closer to the oven, your temperature rises. So even though the oven is making the same heat, the amount of heat you feel depends on how close you are to it.

    With seaweed on the bottom of the reef or lake, the amount of CO2/carbon the seaweed "feels" depends on (among other things) how close the seaweed is to the surface of the water where the air is, because this is where CO2 is being absorbed into the water from the air. This is one of the reasons (besides light) why all the phytoplankton lives near the surface of the water. Seaweed however is far from the water surface, and water that is next to the seaweed (say, 1 cm away) has had so much carbon removed that there might be little carbon remaining. So by making the air more near to the seaweed, it feels and has access to more CO2/carbon. This "near-ness" of air to the seaweed is what makes things work for our filtering needs.
    Last edited by SantaMonica; 08-01-2016 at 11:55 AM.

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    i'm camping here. i like these seaweed

    reminds me of my caulerpa lentillifera which grew so well n lush, but that was past

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    Using Seaweed to get rid of nuisance algae in your aquarium or pond, part 3

    Thinking back now to the oven, and to the heat concentrated inside it, it becomes clear that if that same heat were let out of the oven, your house temperature would get hot, but not near as hot as the oven was. Why? Because the oven concentrated the heat into a small area. And, if you let that same heat outside your house, it would not warm up the outside air at all, for the same reason. If someone did open up all the windows and doors and let the heat out, you would need to stand right next to the oven to get any heat at all. So even though the same process and amount of heat exists, the area that you concentrate it in makes the difference. So going back to photosynthesis, which is the filter we want to use, the amount of filtering it does is based on the concentration of certain things:

    The first is chlorophyll. This is the filtering engine that pulls the nutrients out of the water, and the more of it there is (higher concentration of algae), the more nutrient can be pulled out per hour. The second thing needed in concentration (and to keep the chlorophyll alive) is:

    Light. Any part of the algae that has reduced light cannot pull nutrients out as fast. This is only up to a point however: If the light gets too strong, then the photosynthesis completely stops and the algae die. So the trick is to keep a strong, even, constant level of light concentrated on all the algae at all times, with the exception of the "off" time for the algae to rest. And let's not forget about the concentration of what we want to filter:

    Nutrients. This is like the heat in the house. If you keep the windows and doors shut, you will feel more heat. But if they are open, especially if cold wind is blowing through the house, you will need to be right on top of the oven to warm up. Algae, too, need to "feel" and be near the nutrients, which are stronger near air/water interfaces that supply more CO2.

    Once you are warmed up by the oven, it's time to let the next person stand next to it. Then the next, etc. You can even go into high rotation of letting many new "cold" people stand by the oven for a brief instant, while the others move through the room waiting for their turn. This is how nutrients are supplied in high amounts to the algae; a new group of air/water interfaces is brought in every second, so that the algae see and feel a high concentration of nutrients right next to them, even though a few millimeters away the nutrients are low.

    So let's see how we can build such a filter that let's us concentrate these things.
    Last edited by SantaMonica; 08-01-2016 at 11:55 AM.

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    Using Seaweed to get rid of nuisance algae in your aquarium or pond, part 4

    Let's start building our filter with the understanding of what the algae need to pull nutrients out of the water quickly: Light x Attachment x Turbulence. The light is obvious, and the attachment keeps the algae in place so the turbulence can occur without washing away the algae. The turbulence is the part mostly people don't understand, because they see algae in their tank without much turbulence. What they don't see is the rate of nutrient absorption; it would be very slow without turbulence, sort of like you standing in front of the oven and not letting other people get their turn to warm up.

    Lighting is the simple one: Photosynthesis likes red and blue color light. It absorbs red and blue, and uses it, but it does not use much green. So green is reflected back to you, and that's why lots of plants and algae look green. And for algae, it turns out that mostly red is needed. Matter of fact you can use only red if you want to. 660 nm (nanometers) in particular, which is called "deep red". 630 nm works too. And you can add a little blue, such as 430 nm if you want, but the red does most of the work. "Plant grow" lights can be bought which already have these colors.

    Three main types of attachment material exist: Rocks, strings and screens. Algae have developed a natural enzyme to allow them to bore into solid rock and attach to it, so if you use rock (live rock, or silica rock, for example), then the algae already know what to do. Strings, and screens, which are "new and unfamiliar material" to algae, work by offering the algae places to wrap around and attach back to themself. So while algae may not dissolve holes into nylon string or plastic screen, an algal strand can do a wrap-around and attach back to itself. Once it does this, it's as solid of a grip as with rock.

    Turbulence, as in a thin air/water turbulent layer, is the area where all the work goes into when building, and decisions have to be made how and where you are going to be filtering. You want a lot of turbulent "turnover" touching the algae so that new nutrients are brought to the algae each instant, and you want a very thin layer of water separating the algae from the air, so that what's called the "boundary layer" of water surrounding the algae will be very thin, thus allowing CO2 and nutrients to get in and out of the algae easily. It's like giving everyone a turn to stand in front of the oven to get warm.

    There are three basic ways to provide this air/water turbulence: Rivers, waterfalls, and upflows. A fast flowing river does provide fast water, but the air/water layer is rather thick because the river can get deep easy. More than about a centimeter deep will almost halt any rapid algae growth. Also, light can only reach the growth from the top, so rivers are essentially only 1-sided, which means that the bottom of the river, under the most growth, gets dark easily and can die; this stops your filtering. Therefore since rivers are less efficient, they need to be bigger to give an acceptable amount of filtering.

    Waterfalls solve both of the problems of rivers: The air/water layer stays thin, usually 5 mm, and if the waterfall is flowing down a thin screen with a light on both sides, then the waterfall is 2-sided instead of 1-sided. This light on both sides keeps the "roots" of the algae alive longer, so it holds on longer, thus letting it grow and filter more. Waterfalls must be above the water however, so they take a lot of space. And if the water stops, the growth dries out.

    Upflows, using air bubbles under water, improves upon the air/water turbulent interface of waterfalls because when air bubbles rub the algae, essentially the thickness of the water at that spot is zero for a brief instant. Plus there is an in-and-out swishing of the algae as the bubbles go by. This motion provides the thinnest boundary layer around the algae, and thus offers the least resistance to nutrient and CO2 flow into the algae. Also, upflow cannot dry out, because even if all bubbles stop, the algae just stay under water. And of course, being already under water, they essentially take up no extra space.

    So next time we will start making some things.
    Last edited by SantaMonica; 08-01-2016 at 12:05 PM.

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    Using Seaweed to get rid of nuisance algae in your aquarium or pond, part 5

    Let's start building! The device we'll be using to remove nutrients is called an "algae scrubber". It does exactly as was described in the previous 4 articles and it's called a "scrubber" because it grows algae to "scrub" (remove) nutrients from the water. The first algae scrubber we'll build is a waterfall style, in the shape of a pole. This type of algae scrubber was created by SantaMonica in 2016 to make DIY versions very easy to build. (The very first waterfall design by SantaMonica was in 2008). It also has a great feature: It cannot clog like other filters can

    Here is the drawing of the pole waterfall style algae scrubber made with a pvc pipe. If you already have the water pump, and you don't mind taking the time to rough up the outside of the pvc pole, and if the pole is big enough to put the pump inside it, then the pole is the only part that you'll need to buy (the bottom will need to be sealed shut). This means that this pole version can be made with just one part:





    The pole sits on the bottom of your sump, and water is pumped into the pole (or pulled into the pole if the pump is inside) so that the water overflows out the top of the pole. Or water can be fed into the pole using the overflow tubing from your display. The further down into the pole you put the overflow tubing, the more even and level the water will flow out of the pole to all parts of the pole. And since the pole has a large opening at the top, it can can never clog up with debris or algal growth.

    After overflowing the top of the pole, water flows down the outside of the pole and in doing so makes a thin turbulent air/water interface layer which removes the boundary layers around the algae (meaning it lets you get nearer to the oven as explained in previous articles). The light shines on this turbulence, and grows algae which attaches to the rough surfaces. This growth of course is what removes nutrients from the water because nutrients are what algae consume. Then you just clean the algae off of the pole, and maybe feed some to your fish and snails.

    Although any pipe can be used for the pole, white pvc solid NON-PERFORATED pipe of the sewer/drain "SDR-35" type is thin, super cheap, lightweight, and works great. 4" (10cm) diameter is probably the smallest you'd want to use because light from the light bulb will miss a lot of the pole if the pole is smaller. And if you can go bigger, then 5" or 6" (12.5 or 15cm) diameter pipe would catch even more of the light from the bulb, but of course would take a larger water pump. This pipe is readily available at any pipe, plumbing, or irrigation supply store, or online. You can ask them to cut it to length for you, but usually you have to buy a long length and cut it yourself. The pole must be NON-PERFORATED (meaning solid, no holes drilled in it). Google this: 4 inch pvc solid pipe sdr35 custom lengths

    The pole should definitely be white, because white reflects the most light back to the algae, effectively doubling the amount of light the algae gets and this keeps the "roots" of the algae alive longer. If the roots die and let go, the algae falls off and you lose your filter. Therefore the pole needs to be very, very rough so that the algae can hang on without being washed away by water. There are 3 basic choices of how to do this, and this step is where you will spend most of your DIY time:

    1. A hand drill or Dremel moto-tool with a steel cutter attachment can be used to make the outside of the pole extremely rough like a cactus. This only works with pvc pipe; it does NOT work on acrylic pipe because acrylic does not leave the cactus-like protrusions that you need. Give yourself several hours to do the grinding, and do it outside. You will have a pile of plastic dust on the ground and in your hair, when done.

    2. A sheet of white plastic canvas (knitting screen) can be REALLY roughed up by hand with a wood saw blade, and then wrapped around the pole. The screen will need to fit tightly so that water does not go under the screen. You can glue a peg at the bottom of the pole or a hook at the top, for the screen to sit on, or the screen can just slide all the way to to the bottom of the pole and sit there.

    3. White aquarium gravel, or course sand, can be epoxied to the outside of the pole. A size of 1 to 3 mm gravel works well, and Devcon 2-ton epoxy or similar will be permanent. It may take several applications to cover the entire distance around the pole, but it will be the roughest thing you've ever made. One way to do it is to put the epoxy on the entire pole and let it harden about half way, then roll it through the gravel.

    The water pump needs to be able to supply at least 35 gph per inch (60 lph per cm) of circumference distance around the pole. A 4" pole has a circumference of 4 x 3.14 = 12.6" and thus needs at least 35 x 12.6 = 441 gph of flow out of the top of the pole. Simplified:

    GPH Flow out of top of pole = 110 x pole diameter in inches
    LPH Flow out of top of pole = 188 x pole diameter in cm

    But because of the tallness of the pole, the "head" of the pump needs to be taken into account too. To keep it simple, you could start with a pump that is rated for twice what the calculation says; any extra flow just overflows more, which helps.

    The height of the pole above the sump waterline needs to be enough to catch most of the light from the light bulbs or LEDs. Also, the lights might shine down into the sump water and cause unwated algae growth there, so making the pole taller with rough surfaces at just the upper part helps keep the lights farther away from the sump water. A general starting point is the height of the pole should be at least 8" (20cm) above the waterline if this entire 8" is roughed up. So if the water in the sump is 8" deep, then the pole would be 16" (40cm) tall. The pump will have an 8" head to pump up to. 12" above the waterline is probably easier to work with however, because there is more pole to point the lights at.

    There is no maximum height that the pole could be, however. If you have a large sump and you want the lights way up high, you could make the pole 36" (90cm) above the sump waterline and rough up the top 24" (60cm) of the pole. Of course this greatly increases the head that the pump must handle, and you will need to watch for water that might "spray out" sideways from the pole when the waterfall hits a big piece of algae. (One solution to this is to lay a sheet of plastic sandwhich wrap over the pole so the water stays behind it).

    The base of the pole needs to keep the pole from falling over, and also keep water inside the pole. Two easy ways to do this are either with a sheet of flat plastic glued to the bottom of the pole or with a string attached to the top of the pole that also attaches somewhere to the top of your sump area. If using a string, then a cap will need to be used to seal the bottom of the pole closed. This cap will need to be completely flat, not domed, so that the pole will sit flat. It's hard to tell from online pictures if a cap has a dome or not, so it might be best to buy it at a store. If you use the SDR-35 sewer/drain pole mentioned above in a 4" size, then one cap which works is a 4" number 406 drain cap made by NDS. When turning the water off, the water will drain backwards out of the pump, but if your pump for some reason does not do this then just drill a small hole at the bottom of the pole; it won't affect the pump flow too much. You could plug the hole if you want during normal use.

    A neat space saving version is to use a big enough pole that you can put the water pump inside it, and cap off the bottom of the pole; the pump can pull water into the pole through a hole. The pump will act as a weight to keep the pole in-place, and the top of the pole can be tied with a string. The only space that this version takes up is the diameter of the pole. If you want to go real big, say 8" (20cm) diameter with a flat bottom cap and the pump inside, then you probably won't need a plate on the bottom or a string on the top because it will be stable from the weight of the water alone.

    Cleaning is the fun part, because all that algae (and nutrients!) gets removed from your water. When new, all algae scrubbers in both salt and freshwater will grow a slime that will need the rough surface taken to a sink or outside to be scraped and sprayed off. In saltwater, after the growth gets thick, you might be able to just pull algae off without taking the rough surface to the sink, but freshwater will always need the rough surface to be scraped and sprayed in a sink or outside because freshwater always grows thin slime that you cannot pull off. So the way you want to clean it will determine what version you should build.

    For cleaning, as shown in the picture with a base plate and a separate pump, and if there is no removable screen on the pole, then the pump will need to be disconnected and the pole and base plate lifted out so it can be cleaned in a sink or outside. If the base plate is removable from the pole, then the plate could stay in the sump but removable plates are harder to build. If the water pump is inside the pole, then the whole thing can be taken to your sink or outside. If a removable screen is slid over the pole, then the screen could just be lifted off by itself.

    The lights are basically what fits the pole best. LED or CFL plant-grow lights in the red or pink color are good. A 30 watt light about 6" (15cm) from the pole, on one or several sides, should work well. Algae scrubbers and the lights are normally sized based on how much you feed, but for this pole waterfall version the size of the pole is going to determine a lot because it supports everything. A good starting point is two 30 watt lights, one on each side of the pole. The lights can simply be clipped on to any nearby part of your sump or cabinet.

    Cleaning is every 7 to 14 days, or when growth is thick. The scraped off growth can be thrown away or put into your garden or lawn, or if it's thick green seaweed from saltwater then some of it can be fed to your dogs and cats. Some can even be fed back to your fish and snails; that's what a lot of them eat naturally.

    So happy DIY'ing... and post pics of your build for others to see!

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