Introduction: Simple Algae Home CO2 Scrubber - Part II Algae Cultures and Breeding

In Part I we built a simple home CO2 scrubber using algae. I'm writing this instructable to demonstrate how to culture and cultivate algae using more or less laboratory style procedures but substituting some readily available items for more traditional laboratory glassware.

I encourage you to experiment and understand how to successfully cultivate algae. The techniques and process outlined here will work for most algae strains.

Please bear with me, this is a work in progress. I normally publish open source software where the policy is "Publish early and often". The content is constantly being revised and I'm open to collaboration on many elements.

For instance the crude incubator could easily be supplemented with a sound design using plastic sheets with hinged access panels and portholes with oversized rubber gloves mounted in them. And so on.

In Part I we used a readily available algae source to create a healthy algae culture which gets fed with air, sunlight and liquid plant food to provide CO2 scrubbing on a small scale.

The original sample probably had a wide variety of micro-organisms, many of which are probably bubbling harmlessly away in the soup. But we're not here to create bio-soup, we're here to make algae.

It will be very nice for you if you have a microscope but you do not need one. It should be possible to obtain a single species algae culture and breed it up to production reactor populations without one. If you happen to have one, as I do not, then you can whole hog nuts and breed a pure culture from a single cell.

In any event if you want to get serious about algae you'll need to learn to culture and cultivate algae. These skills can be applied to special purpose algae species obtained from the appropriate channels. There is an appendix with more detail on obtaining single species specialized algae cultures from universities and research institutions. Expect to pay about $75 for a culture which, with sound breeding practices, is sufficient to create pure feedstock. Put some of that in a bioreactor full of pure water, nutrients and you're done.

For the rest of us we're going to isolate some algae cultures from our birdbath sample in a Petri dish (or substitute such as I use) with Agar (or a substitute).

From that we're going to identify some single culture strains (one batch of green stuff). We're going to multiply those strains in some small bottles to understand the process of scaling up a culture.

At the end we're going to create our production breeder reactor which will consist of one culture reactor which is used to maintain a constant population and two breeder reactors used to create feedstock for production reactors (in the case of CO2 scrubbers) or for feeder reactors which are moderate sized (3-5 gallon) reactors for producing feedstock for above ground pool based open pond or vertical growth closed reactor systems.

Okay with all said and done let's take a look at what we're going to need...

Step 1: Bill of Materials

1 case Ball brand Mason jars - If you're going to breed algae you're going to have a variety of strains to nurture at various stages. Just do yourself a favor and get a case of the quart size. There is also a very handy half gallon size which is suitable for larger cultures.

A lab journal for recording strains, experiments and results.

Several .5L clear plastic water bottles, labels removed and run through the dishwasher.

A couple of 6+ inch pieces of reasonably stiff wire, picture hanger wire isn't stiff enough and coat hanger wire is the worst case because it's hard to bend but will do.

Calcium Carbonate - Chalk or 500 mg Calcium dietary supplement made from calcium carbonate

Some soil to use for preparing algae media. Should be good rich soil from a variety of sources.

There is nothing special about the particular soil used However, several considerations are probably important, including the following:

1. The soil should be a loam, with a mixture of particle sizes (sand, silt, clay).
2. It should contain a moderate amount (15 - 20%) of very-well-decomposed organic matter.
3. It must not contain pesticides, especially herbicides.
4. It should be soil that has been aged (preferably for 6 months or more) under moist conditions and not, for example, fresh potting soil, soil that contains fresh manure, or soil to which a commercial fertilizer was recently applied.
5. A slightly acidic soil derived from granite or other igneous rock is preferable to soil obtained from calcareous soils.
6. Particulate matter in the soil such as gravel, Perlite, or vermiculite are not necessarily damaging but can be of considerable nuisance when wishing to quantitate the amount of soil used in the medium or when handling algae that are physically associated with the soil. Particulate organic matter, such as compost that is only partially degraded, should be avoided "altogether.

Aluminum cake pan for heating and foil to line it. 2 quart pot with cover for boiling.

6 Petri dishes (see picture) or a reasonable substitute. Most scientific supply stores will offer prepared dishes with Agar. If these are available use them.
Almost any shallow, wide mouthed container that can be easily covered with Saran Wrap(TM) and sealed with a rubber band will do
I will be using baby food jars with the labels removed.

Glassware will need to be cleaned thoroughly or sterlized between uses.

At minimum place them opening down in the dishwasher and when removing them after the cycle completes keep them upside down until the cap is screwed on. Keep the cap inverted until just before closing the bottle. This will minimize accidental contamination.

A couple of gallons of fresh water will do nicely. Its probably worthwhile to pick up one of the 3 gallon bottles of fresh water available at the supermarket. Especially if you're thinking about any sort of small volume production you will need several of these for use as feeder reactors.

Materials to build the culture incubator. This will be used to breed algae at various stages as we reduce the population samples, then incubate the targets and attempt to get identifiable algae strains. It is not strictly speaking necessary to use an incubator for the hobbyist. For anyone who is serious about cultivating algae and plans on obtaining cultures of more exotic algae from scientific and academic supply houses an incubator is probably appropriate.

20 gallon aquarium (does not need to be watetight)
Heavyweight clear plastic
The side from a zipper plastic blanket bag my wife had
Plastic garbage bag would be okay. White is best
Strong Tape
Small lamp that can use up to 75-watt bulb
Bulb size will vary based on desired temperature
On/Off electrical timer set for 18/6 on/off cycle
Thermometer (preferably in a clear plastic case)
If anyone knows of an inexpensive temperature controlled thermostat I'd be pleased to hear it.

Step 2: Prepare the Soilwater Medium

Soilwater is an essential component for cultivating algae. While the liquid plant food provides most of the essential nutrient algae also require other trace minerals which are extracted from the soil. In this step we will create a standard soil-water medium is used to supplement the plant nutrients.

First we will prepare a standardized green house soil based on a recipe from the University of Texas at Austin.

This is an adaptation of E.G. Pringsheim's biphasic soil-water medium. Variations of this medium are suitable for isolation and for growing algae to secure "normal" growth forms. Soilwater is not a well-defined medium, yet not all soil is suitable for culturing a broad range of algae.

UTEX uses some greenhouse soil they got from Indiana University. For a long shelf life it must be kept dry and away from light. UTEX keeps it in sealed 5-gallon plastic containers, keep a few quarts around in Mason jars for future use.

Prior to its use in soil-water media, treat soil in batches by placing it in a heat-resistant pan lined with aluminum foil, fill the soil to a so depth of 1/4 inch, and bake at 300 degrees (150C) for 2 hours. After it cools, cover the pan with aluminum foil and store in darkness at room temperature. Avoid excessive moisture during storage.

Now its time to prepare the medium. Add 5 tsps of green house soil for each liter of water and 5mg of calcium carbonate. Bring to a low boil and simmer for 15 minutes. Cover, allow to cool and refrigerate. Repeat daily for 3 days. Allow to refrigerate overnight and bring to room temperature before use.

Use a large pot, make a couple of gallons. Parcel it up into the Mason jars and save what you don't use.

This is the water medium we will use to culture our algae.

Step 3: Preparing Agar and Culture Plates

Prepared agar plates are inexpensive and readily available from scientific supply stores.

If, for whatever reason you don't care to use prepared plates you can make agar plates from tablet, powdered, or bottled agar by following a few simple instructions.

Agar can be obtained from health food stores and high end supermarkets with health food departments. The clerks will be able to help you if you ask if they carry 'the dietary supplement agar and calcium supplements with calcium carbonate because a friend recommended them" instead "Hey, you guys got any stuff for breeding algae?"

Keep the Petri dishes or other culturing containers clean (sterile) and closed until just before use. Lift the lid as little as possible when filling the containers and cover immediately to prevent contamination.

Preparing Tablet or Powdered Agar:

Dissolve 1 bar, 10 tablets or 7 grams of powdered agar in 1/2 quart of the soilwater we prepared in the last step. Warm the agar in a hot water bath by placing it in a glass bottle. Heat water on the stove until just about boiling, remove from heat and place the agar bottle in the water. The microwave is another good way. Simply heat up a bowl of water and place the bottle with agar in the center.

As it warms the agar will begin to melt, warm the agar until it becomes liquid. Remove it from the heat and let it cool a bit. Then add 7 drops of Schultz Liquid Plant food and mix well to distribute the nutrient evenly throughout the agar.

Pour enough of the liquid into each container to cover the bottom by about 1/8 inch and place on a counter to cool. The agar will set up like stiff gelatin at room temperature.

If the agar doesn't set up properly try again with more agar. Extra agar may be stored and re-liquified in a hot water bath. Keep the samples covered and be careful to avoid contamination.

Storage: Stack agar plates upside down in the refrigerator. Do Not Freeze! The purpose of placing the plates upside down is to prevent condensation from dripping down onto the agar surface which could then facilitate movement of organisms between colonies.

For those who want to more rigidly controlled independent work the formulation for LB (Luria Bertani general purpose nutrient agar) is: 9.1 g/L tryptone, 4.6 g/L yeast extract, 4.6 g/L NaCl, and 13.7 g/L agar. 500 ml of agar will pour ~ 25 large Petri dishes (100 mm diameter) or 50 small Petri dishes (60 mm diameter).

Next we're going to build an incubator for culturing algae. It's a warm, safe place for the algae to grow in controlled conditions as the population is bred up.

Step 4: Building the Culture Incubator

This is used to keep the cultures in a warm, well lit environment free from contamination. The plastic "door" drops down to provide a shield and care should be taken. Okay, the world will not end if your algae culture is tainted or if the aseptic conditions are compromised. But what the heck if you're going to go through all this wash your hands and keep things covered as much as possible.

20 gallon aquarium (does not need to be watetight)
Heavyweight clear plastic
Strong Tape
Small lamp that can use up to 75-watt bulb
Thermometer (preferably in a clear plastic case)

Turn the aquarium so the opening faces the front instead of the top
Cut the plastic slightly wider than the opening and about 2 inches longer than the height of the opening
Tape the plastic to the top of the aquarium so that the plastic falls over the opening. This is the door
Place the lamp in the aquarium, letting the cord hang out the front
Place the thermometer in the aquarium so that you can read it without opening the "door"
Experiment with different sized bulbs until you find one that keeps the temperature around 70 degrees ( for algae breeding, for stock culture maintenance the algae is maintained at a lower temperature)

Okay, that' it. In the next step we're going to place some culture samples on the agar plates we created in the last step and place them in the incubator. After about 2-3 an algae culture should begin to be visible on the agar.

Step 5: Preparing to Create the Culture

The basic methods of algal culture have changed little over the years and the various steps in the process leading to production-scale cultures are shown in the picture.

Now we need the wire in the bill of materials. Take a piece of wire about 6" or long enough to reach to the bottom of the culture plates you are using. For Petri dishes this is obviously quite short but if you're using mayonnaise jars you'll need something long.

Using a pair of needle nose pliers make a loop in the end of the wire. Bend this at a 90 degree angle and wrap some tape around the other end to form a handle. Using pliers hold the round tip in a flame (match or candle) until the tip glows red to sterilize it. Let it cool down in the incubator.

We're going to use this tool to spread tiny samples of algae on the agar plates and allowed to grow. After a few days we'll identify some uniform populations and we'll use this tool again to gather samples from those populations and put them in the soilwater media to breed an identifiable algae strain.

Now we're going to get our algae sample. If you're using the reactor we built in Part I then you'll want to extract a small portion of that for easy handling in the incubator. Remove the bubbler assembly from the reactor. Note: It's easiest if you hold the top and turn the bottle underneath it. You'll want to have a pitcher or tall glass handy to put it in.

Now we're going to fill the Mason jar at least half way. To reduce contamination risk open the lid of the Mason jar only enough to allow easy pouring. Put the lid back on the Mason jar and place it in the incubator.

Top of the culture reactor with soilwater media and replace the bubbler. This method insures that there is a steady supply of culture media available.

Place as many Petri dishes in the incubator as you want to culture, probably 4-6 is enough. Do not remove the lids from the culture plates until you use them.

Now we have to record this strain and its heritage. Where did it come from and when?

I number my strains using a location name and a date in YYYYMMDD format for easy comparison. A '-S' suffix identifies samples and cultures from that sample are identified with '-CXX' extensions.

So a sample from the Delta Mendota canal from Jan 1, 2008 would be DM-20080101-S and the cultures from that would be identified with -CXX extension indicating which culture. Record the culture ID and other information in the lab journal.

Create a label (masking tape and pen will do) and label each of the Petri with it's culture identifier. This isn't necessarily the order in which the plates are filled but it is the sample ID the culture(s) which result will have.

Now we're ready to create our first culture. Go wash your hands thoroughly up to the elbows. Let me clarify what this means. A surgeon will scrub each surface of the hand including the sides and tips of fingers at least 10 times. That would be overkill.

Step 6: Sampling the Algae Medium

Okay now we're going to move completely inside the incubator where we have our sample tool, the Mason jar of algae media and our Petri dishes. Turn off the light first (just in case you were warming things up).

Remove the lid from the Mason jar and using they eyedropper dip into the algae medium and get a sample. Put the lid back on the mason jar and open up Petri dish #1. Put one drop of algae medium onto the plate and use the sample wand to make a Z shape most of the way across the agar but not all the way to the edge.

Close the Petri dish and repeat this process for each sample you take. When you are done remove the sample wand and the Mason jar from the incubator. Hopefully you've placed the incubator in a location where light is readily available (indoors near a window?) and the light bulb supplements the heat. Use a lower wattage for steady supply since the heat will build up in the incubator over time. This is okay algae like it hot.

After about 5 or 6 days the cells will have grown enough to form colonies. These colonies on this first streak plate often tend to grow together, so it is difficult to pick off colonies with only one species. You may have to scrape some colonies off the first plate and re-streak them on a second plate in order to get good separation.

Okay now we're going to breed the individual colonies to produce cultures of the individual species.

Step 7: Breeding the Culture

In order to get visible growth as quickly as possible we will stage the individual colonies in a series of ever increasing reactors until we get a production batch. The first of these we'll call a multiplier reactor. Use a small flask ( 150 ml or so ), a baby food jar or a mason jar with a small amount of prepared nutrient medium (soilwater + plant food ).

Prepare as many jars as you have clearly separated individual colonies to sample. With multiple tries you will become adept at streaking the plates in ways which result in more colonies (and require less 'seed' stock).

Label the jars to match the sample designation and add a serial culture ID. Note in the log book anything particularly interesting, size, color what have you that might differentiate this culture from others.

Once you can clearly identify individual colonies scrape them off and place them in the multiplier reactors, cover the reactors and leave in the incubator. After a few days you should have visible algae growth.

If you have a microscope you should be able to track initial population growth. The chart shows algae growth rates through the exponential portion of the growth curve. After that algae shadowing becomes to come into effect.

With a microscope it is possible to start with a known population ( in theory one cell to provide a uni-strain culture) and breed up.

These reactors have a finite amount of nutrient, and when that is exhausted, the growth will stop and eventually they die. Experience will teach how long these types of cultures last and help to identify peak color conditions.

After that to continue the culture you must "sub-culture" by transferring this culture into a culture reactor containing fresh growth medium. I typically transfer from the breeder reactor to a .5 ml water bottle containing fresh growth medium. Open the lid a quarter to a half turn (you want it water tight but not air tight to vent). It is possible to use a bubbler apparatus on these but I find if I turn them upside down and shake them a couple of times a day they do fine.

After a week or two the breeder reactor will reach max density and should be transferred to a culture reactor such as one the we built in part I.

The pump we use in Part I will easily support multiple reactor vessels. These should be connected in parallel Single and multiple 'Tee' adapters are available at PetSmart and other fine aquarium supply stores as well as the specialty hardware section of your local ACE or Lowe's.

Simply split the output from the pump and distribute it to as many culture reactors as will bubble air through.

Monitor the color of the algae and experiment with the amount of nutrient solution required to maintain growth rates.

At this point you should have several well identified strains with which to experiment with variations in light, nutrient and so on and so forth.

Step 8: Maintenance of Stock and Starter Cultures

Stock cultures, otherwise known as master cultures, of the preferred species are the basic foundation of culture. They are normally supplied as monospecific (uni-algal) cultures from reputable culture collections maintained by national institutions or research laboratories. Since they are valuable, they are normally kept in specialized maintenance media, on nutrient enriched agar plates or slopes, under closely controlled conditions of temperature and illumination. A special area or room off the algal culture room is usually allocated to this purpose.

Stock cultures are used only to provide lines of starter cultures (also known as inocula) when required. Every effort should be made to minimize the risk of contaminating the stock and starter cultures with competing microorganisms. The sterile procedures described below should be followed to ensure that contamination does not occur.

Stock cultures are normally kept in small, transparent, sterilizable containers. For example, 500 ml glass, flat-bottomed boiling or conical flasks fitted with a cotton wool plug at the neck, suitable for containing 250 ml of sterile medium, are ideal. Stock cultures are also often maintained in agar medium with suitable nutrients in Petri dishes or on slopes in test tubes.

Stock cultures are best kept in a cooled incubator at 4 to 12�C (50F) (according to preference), illuminated by low wattage (8W) fluorescent lamps or LED bulbs that provide at least 450 lux.

Alternatively they can be kept in cool conditions close to a north-facing window (out of direct sunlight), or in a cool room illuminated by fluorescent lamps. The objective is not to allow rapid growth, but to maintain the cultures in good condition. The cultures are not aerated, nor is carbon dioxide introduced.

It is necessary to sub-culture stock cultures at monthly intervals to maintain them in a vigorous and healthy state. Simply put 1-1.5 oz stock culture into another reactor containing nutrient medium.

The original stock culture can be kept for a few weeks in the event that the new stock culture fails to grow. The stock culture transfer procedure is best performed in a cabinet that has been sterilized by ultra-violet light to further reduce the risk of contamination.

Step 9: For More Information...


gkiriwn (author)2015-11-26

Hello, I have recently stumbled upon this post and I need help. I ordered a sample of Spirulina Seawater algae and it came in a test tube with about 10ml of the culture. How can I grow more from such a small sample? I want to go large scale but what accommodations do I need? (Housing, Water type, medium, temp, air pump, Etc.)

Thank you!

SHOE0007 (author)2015-08-01

I doing an experimental type of agar which contains 99% dark coca for antioxidants and vitamins with yeast extract and chemicals to inhibit fungi and bacteria growth. Expect I use clover cuttings and seeds to grow. Here is the recipe.

Fungicidal yeast vitamin and mineral agar with glucose

and copper sulfate instead of sodium dichloroisocyanurate.

100 ml.

Tea tree oil=1 ml

copper sulfate = 100 mg.

dark Cocoa 99% = 5 g.

Sugarcane Molasses = 10 g.

Yeast extract = 5 g.

Grams Protien at least 3 g.

Vitamin B1 = 0.75 g +0.0041 g = 0.754 g

Vitamin B2 = 0.75 g +0.0046 g = 0.755 g.

Vitamin B3 = 1.5 g +0.016 g = 1.516 g.

Vitamin B12 = 0.5 g + 0.000021 g = 0.500021 g.

Folic acid = 1 g + 0.0004 g = 1.0004 g.

Biotin = 54 mcg. Trace.

Pantothenic acid= 12.5 mg.

Vitamin K3 = 25 mcg. Trace.

5.8 mg 1,3-diphenylurea *10 ml = 58 mg.

58 mg *20 ml/120 ml = 9.66 mg.

Requires cytokinins 1 mg per ml.

requires 20 mg.

Requires 20 ml.

Limit solubilty of 15 mg per 100 ml.

150 mg per L, divided by 10 gives 15 mg per 100 ml.

increased solubility with heat 90 to 100 degrees C.

Soak seeds (clover) 5 g per L. 10 g per 800 ml.

So soak seeds in 5 g per L of sodium dichloroisocyanurate.

soak seeds in water to reduce sodium dichloroisocyanurate

levels in seeds.



Sucrose = 16 g.

Fructose and glucose = 13 g.

Plus 5 g glucose.

Sodium salt: 160 mg + 700 mg = 860 mg or 0.860 g salt.

Calcium carbonate = 0.3 g + 4 mg = 304 mg.

Iodine (potasium iodide)= 0.015 mg.

Iron (iron fumarate) = 6 mg + 8 mg = 14 mg.

Manganese (II) sulfate = 5.5 mg.

Chronium (III) chloride = 35 mcg.

Selenium salt of sodium = 55 mcg.

Magnessium = 8 mg.

Zinc oxide = 11 mg

Potassium = 180 mg.

Malachite green = 22.5 mg

10 g *0.225/100 = 0.0225 g *1000 = 22.5 mg in 100 ml

22.5 mg/ 10 g + 1g + 5g+ 1g+ 20 g + 100 g = for 20 ml = 3.3 mg MG.

Both copper sulfate and Malachite green act as potent fungicides potentially killing the mold. The dark color agar will absorb light from the seeds but the MG will be trapped and slowly enter the seeds.

May need to adjust tree tea oil, malchite green and copper sulfate dosage.

HappyCupcake4002 (author)2015-01-11


talenco (author)2014-07-10

How can producing algae benefit from local conditions such as weather, climate, in-water application etc. so that it becomes a natural resource activity?

egbertfitzwilly (author)talenco2014-07-12

In Part One there is are two PDFs attached that speak to this. One is a summary of the NREL research and the other is actually a business model produced by the University of Alabama. The NREL concluded that algae grows everyplace naturally and the local species should be used since they will inevitably dominate any open air production methodology.

The UofA study concludes that algae can be produced sustainably and profitably in conjunction with fish farming.

Overall while clearly tank based methods provide environmental control far beyond local ambient conditions the open air methods ( raceways, ponds and son on ) might need a light break of some sort in areas which have extreme sunlight conditions such as California's Central Valley.

Does that answer your question?

talenco (author)egbertfitzwilly2014-07-13

Yes it does
One article mentions the requirement for two outside sources: a concentrated supply of CO2 and a saline solution to act as a medium.

Can seawater be used as a medium?

Thanks again

egbertfitzwilly (author)talenco2014-07-13

There are saltwater algae so the technology should generally transfer. A concentrated from of CO2 isn't required but the algae does need it in some form. Ambient CO2 should be sufficient. Do not forget that the algae also require other nutrients which must be supplied by some mechanism.

zwuckl (author)2014-02-21

Hey there.

I stumbled upon this instructable by recognizing your cover picture. The plant on the agar plate is clearly not an alga, but the moss Physcomitrella patens. As a matter of fact I am currently working in the lab of Ralf Reski, where this moss is our preferred organism for studies molecular biology. In addition, this is where this exact photo was made some years ago ;)

egbertfitzwilly (author)zwuckl2014-03-27

Yeah, I hijacked this photo to illustrate the instructable.

RUSTY_duck4 (author)2013-11-21

Pretty expensive


I'm not sure I understand this comment. Check garage sales, you should be able to find a used aquarium for very little. Also check with your local pet supply store, they may have one ( or know of a customer ) that leaks.

astral_mage (author)2013-11-19

try finding 1 from ? should have every thing u need, but will take up too a month to get to u tho....

Prodiver255 (author)2012-12-11

In regards to the soil water media, would it be possible to use aquatic soil planting media in place of green house soil? If not, how would one procure green house soil? Also, does the permanent reactor vessel need to be constantly 'topped up' with freshly cultured algae or will it become mostly self sufficient? Thanks


Any reasonablly rich soil should work, as well as a few drops of liquid plant food. A permanent reactor should be self sustaining except for the tendency of algae to spontaneously flocculate and the whole colony dies for no apparent reason. So it is prudent to maintain an algae culture for restarting. The documents I've attached to the instructable contain multiple designs for production algae ponds.

Kernel770 (author)2012-07-31

Hi, really awesome instructable!
Considering the soilwater medium - I'm not sure if I understood this right; every day for three days, I add 5 tsps "cooked soil" and 5mg CaCO3 per liter - so after three days I would have 15 tsps and 15 mg per liter? (excuse me for this question)
kind regards


No, only the boiling and simmering is repeated for 3 days. Mix, boil it simmer for 15 minutes, store overnight, boil it, simmer for 15 minutes, store overnight, boil it, simmer for 15 minutes.

FuzzeeDee (author)2012-07-30

A temp controlled floating heater can be found at any pet store handling aquarium supplies.
• • • Fuzzee Dee OUT • • • }~{ <> }~{ ^~^ :-> 

blob800 (author)2012-03-17

Is the baking of the greenhouse soil only required in order to sterilize it? Instead of baking in the oven, could I just sterilize it in my pressure cooker, or is the baking step required? (I would assume that baking it would get pretty smelly)

egbertfitzwilly (author)blob8002012-03-17

Absolutely, a pressure cooker would be ideal. I can't speak authoritatively to how long one might 'cook' the brew, you might check out the guidelines for 'autoclaving' which is a similar process.

AlexHRG (author)2012-01-23

Hi, first of all great Instructable! I'm more technical-minded and i have no clue what to do with biological "stuff", so this step-by-step was extremely informative!

I am wondering if you would have any source or reference to identify the cultures that have been developed? Something like a quick reference sheet for the most popular algaes found would be most helpful...

egbertfitzwilly (author)AlexHRG2012-02-11

I cannot speak authoritatively to this issue. It has several dimensions. Almost all plants are oil bearing, its a matter of how much oil one can effectively obtain. You will need an expeller press which can be purchased or fabricated depending on your skills and equipment.

Algae based biodiesel is produced with 200 proof ethanol rather than methanol, although I am not familiar with the process. To produce the ethanol you'll need to get a small fuel producers license from the ATF. It's fairly straightforward.

If you live in the southeast you might want to read the attached documents. There is a study of the folks at University of Alabama that includes a very nice algae based business model that might be exploitable.

TJBrooks (author)2012-01-20

what plants would you suggest to press oils from to produce biodiesel from methanol or ethanol that might be native to or can be grown in southeastern US?

egbertfitzwilly (author)TJBrooks2012-02-11

I cannot speak authoritatively to this issue. It has several dimensions. Almost all plants are oil bearing, its a matter of how much oil one can effectively obtain. You will need an expeller press which can be purchased or fabricated depending on your skills and equipment.

Algae based biodiesel is produced with 200 proof ethanol rather than methanol, although I am not familiar with the process. To produce the ethanol you'll need to get a small fuel producers license from the ATF. It's fairly straightforward.

If you live in the southeast you might want to read the attached documents. There is a study of the folks at University of Alabama that includes a very nice algae based business model that might be exploitable.

maliksudhir (author)2011-08-24

Hi ,
Can any one help me out in some calculation work its really very urgent , please help me out ..... i need to consume 1932.3kg/hr of CO2 with the help of Algae in a pond (water) for example Raceway pond , so i need to know the specific area to construct that pond and its sizing and dimension (length,etc) and the quantity of water needed and amount of algae used so that it easily consumes the mentioned amount of CO2 rate per hour..... please help me out soon you can also drop your suggestion and questions if any my email id is : ....i will be waiting for your reply soon and i'll be highly thankful to you, if someone can help please do tell me its very urgent....

Thank you

ronmaggi (author)2010-09-05

Everyone talks about making this solar powered, but no one has talked about making it wind powered. Perhaps a small Savonius Wind Turbine belted to a small mechanical air pump inside the house?

egbertfitzwilly (author)ronmaggi2010-09-05

Actually I've got another design I've been trying to get someone to use with a Savonius or other small VAWT. In my design the wind power is used directly to provide lift in a tank. The media needs to rotate from the bottom to the top in approximately a 6 second cycle. I was thinking of a VAWT driving Archimede's screw. I'd be happy to advise if you want to take a crack at it.


I am new to this sight and very passionate about alternative energy sources. I say these things with only the deepest respect and encouragement. I love what you have posted and plan on trying to cultivate my own algae buffers. I have done a fair amount of involuntary research into wind power and felt that I could help. Wind is fairly unreliable, however when in supply there is usually alot. As a power source instead of using it to create voltage it is better stored as air pressure. A deep cycle battery (car batttery) looses power over time reducing efficiency. Either hooking the turbine up to a compressor or direct through a sterling engine pump into a reservoir would supply an extremely reliable drive source for the Archimedes screw. A HAWT would work better for drive however due to higher efficiency and torque through the length of the blades. The Savonius blades might be better suited in the tank only in a horizontal axis the bubbles would cause the Savonius blades to spin mixing the media and providing a second source of power generation.


Tnanks for taking the time to share your comments. if I can help with your projects in any way please let me know.

aasong2001 (author)2009-09-30

Dear sir,Thank you very much of your thoroughly instruction. Is the purpose to "block out the light and keep it warm" by as you said to "close the jar and cover with cloth"? I intend to squeeze some "biodisel" out from Algae,how many of my "dark green bottle(1L/bottle)" needed in order to get 1 gallon of biodisel?

beehard44 (author)aasong20012010-03-26

squeeze it


Closing the jar and covering with a cloth will shut off additional light and CO2 so the algae will die and settle out. I have no information about making biodiesel from algae. There are many studies which say this is not a workable solution using native algae. If your goal is to produce biodiesel I can offer some insight into that process. Many people don't know that biodiesel can be produce with either methanol or high grade ethanol (200 proof). It is relatively easy to make 200 proof ethanol using two pass distillation in a traditional still. Oil can be crushed from many available local species using a simple oil press, often using a manual hydraulic jack for additional pressure. Sodium Hydroxide (lye) can be easily made using a microbial fuel cell (see my other instructables) to provide low voltage electricity for converting saltwater to lye. This is probably the best way to get biodiesel in any usable quantity for a stove or car.

aasong2001 (author)2009-09-29

Dear Sir I have many "Dark Green" bottles,but in some of them which I can see little crust, not much,I try to harvest it ,but get nothing more than my bald head,would you please instruct me to harvest it. Dark green mean good density right?mean grow success right? Thank you so much!


Yes, dark green indicates successful breeding. There are several ways to harvest. Let me ask how do you want to use the algae? The absolutely simplest way to harvest is to close the jar and cover it with a cloth for a day or two. The algae will all die and settle out forming a very dark green sludge. Carefully pour off the top portion of water ( as much of the clear water as you can get out the better ). The remaining sludge can be sun dried in large, shallow trays. The resulting dried algae can be used for livestock feed, experimenting with biodiesel. The sludge can also be used directly as a fertilizer simply by spreading it around and working it into the soil. The algae can also be used in a microbial fuel cell similar to the ones in my other instructables to generate a trickle charge of electricity for recharging small batteries. The effectiveness of this is increased if one uses a 'joule thief' ( search instructables for that term).

Uncle Kudzu (author)2009-02-28

is my 4-liter algae filled aquarium a CO2 scrubber in the same way that your soda pop bottle is? i have turned off my tiny air pump so as impede the escape of CO2 at the surface, an arrangement that the other plants in the tank seem to like.


Yes, any green plant scrubs. It is my understanding that chlorella is the most efficient in terms of population density. There seems to be a strong scientific consensus that chlorella is why we have an oxygen atmosphere. Are you trying to grow algae? You might consider one of those of those overflow aerators to maximize exposure. This key issue at some point becomes light penetration which is about an inch and a half. Now the algae only require about 1-10E24 or so seconds to absorb a photon so the overflow aerators can increase population density.


no, i wasn't trying to grow algae in my aquarium, but i may have to reconsider in light of the benefits i'm reading about here. i had no idea that i had a little CO2 scrubber on the shelf beside me!

algae is the bane of the planted aquarium enthusiast; expose an aquarium to enough light to grow plants, and algae is inevitable. i have bacopa, anubias and Java moss in the tank, with recently added duckweed to actually compete with the algae for nutrients.

duckweed grows like, well, like a weed. i wonder if a dedicated container of algae with a surface of duckweed might be more efficient?

this is all very interesting; thanks for the detailed instructable!


It is my personal belief that the role of algae as part of a carbon recycling chain is being overlooked. Depending on the nature of your enthusiasm you might consider algae as planted aquarium plants.

The folks have UTEX ( have a wide variety of algae cutlures available, including some very exotic breeds.

If you flip that aquarium on its side (perhaps emptying it beforehand would be a good idea) and make it into an incubator you can culture a wide variety of carbon scrubbing and quite exotic aquatic plants.

Once you figure out how to stabilize various cultures a CO2 scrubber makes a perfect gift. I would be very pleased to assist you in working out a pilot project.


there is mt+ & mt-,how do you distinct it? I follow your instruction and I get the "green",but 2-3 days later it turn to yellow green,then pale yellow to light gray, why? are they dyeing?how to rescued them? Thank you!


There are several possibilites. First algae cultures are given to spontaneously crashing but that normally happens after several weeks. Are they getting plenty of CO2? You might need to add a few drops of liquid plant periodically as well. If you have a pH test kit (say for a swimming pool) you might test the pH. If the water becomes saturated with CO2 ( too much pump, not enough water ) it can become highly acidic which will kill the algae. If you add water you need to make sure its dechlorinated.


i must say that i have never thought about algae as an ornamental aquarium plant. i'm certainly rethinking its status as a total nuisance, though. it's almost impossible not to grow the stuff, so why not put something that's so determined to thrive to good use?

neptune01 (author)2009-07-17

Great read! I do have a question: What is the direct benefit of growing algae beside that is a Co2 scrubber? What can dry algae be used for? If you burn this – are there some toxic gases?


Dried algae can be used a livestock feed supplement. In a study by the NREL it was determined that up 25% of alfalfa or barley livestock feed could be safely replaced with dried algae. That was the limit of the experiment, a higher ratio may also perform well.

It is, of course, in use now as a dietary supplement for humans. There are corners of the world where it is not inconcievable that algae could become the main ingredient in Soylent Green.

Biodiesel can be made from algae using an ethanol and brine process however the processing problems to obtain algae in sufficient quantities for production use are significant.

Exxon just announced a 5 year, $500B program to develop genetically engineered algae for biofuels but they will be starting almost from scratch.

And you can make biochar from it for long term sequestration. There are gasses released which need to be contained by some method. I address this in one of my other instructables:

gleipnir (author)2009-04-25

you could use an aquarium heater to keep the algae cultures at a constant temperature.

krujh2 (author)2009-03-07

Kind of random but I want to say that Algae actually has feelings. When it's Green it's happy, but when it's red it's sad. So be nice to the algae, it has feelings too!

egbertfitzwilly (author)krujh22009-03-07

Talking to them or blowing through the air hose periodically will make them happy. But then so would any additional source of CO2.

coolsciencetech (author)2009-03-07

one thing that you must consider is the amount of co2 produced to make the electricity to power the pump. I would be interested to know how much co2 it takes out of the air INCLUDING the amount of co2 produced to run the system. I like the idea of solar powering it like mattameo213 said.


I'd be very pleased to consider suggestions on an alternative energy solution. As far as I can tell the solar footprint is fairly significant compared to the reactor size. The reactor design allocates one liter to scrub its entire annual CO2 footprint (based on a 1.8W pump) in the first 6 weeks. After that the device is a net CO2 consumer. The second liter scrubs the CO2 for an additional 17 kWH (based on the EPA report (see the URL in step 8).

mattameo213 (author)2009-03-01

Great Job! Though I feel that this is a little drawn out, but necessary. I have an idea for making the entire project solar powered, If it works I'll post about it.