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Here you go Harold.

An Algae culture topic.


So I'm looking at Spirulina. Its easy enough to grow and its a 99.9% complete food. The methods and inputs aren't costly or complicated and it runs on Urine(welcome news for TC I'm sure), sunlight, oxygen, and at 10.3 and over PH, it is germ free. This is the last key, freeing AP to finally become self sustaining. As hobbyist we can supplement with worms, larvae, food scraps etc, but to answer the question of human sustainability we really need to get more serious, don't you agree?


Kobus I know you have been experimenting with this for some time now, if you'd like, design a simple model, I sure we can persuade Sylvia to market it for AP use. We have to start somewhere, how about here?

So I've done a bit of looking into this topic but haven't had much time to really get into it. A wider range pH test method is needed than what we in Aquaponics are used to but aside from that I expect it shouldn't be too hard.

Here is a link to a web site that is already selling kits and starter culture
Algae Lab

And here are the pdf instructions for the kit they sell.

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It's gonna take more than Just spirulina to feed the tilapia.


And I expect it will take quite a lot of space to grow a substantial supplement of spirulina for the tilapia.


Keep in mind that the kit will usually take quite some time to get up to the production of a tablespoon every other day.  I would expect you would probably need a bout 20 gallons of algae system to feed two tilapia a fairly large supplement to their diet with spirulina.

I'm confused in previous posts with links to studies there was talk of feeding the fish just spirulina as a sustainable food

Well I suspect it could be done but it will take more than say a 10 gallon aquarium to do it since I don't think you are going to totally feed 20 tilapia on a spoon full of material every two days.


And keep in mind you need fertilizer sun and controlled temperatures and pH to grow lots of spirulina.  This is doable but I don't want people to think that you get something for nothing.  You are not going to be able to grow 100% of your fish feed in a 10, 20 or probably even 50 gallon aquarium (ok if your fish are just a couple small fish you might be able to manage growing all their feed in a 50 gallon aquarium.)  Like with duckweed, you need space and nutrients to grow lots of it.

Hi TC,

I am aware you're working on putting a SP kit together. SP is grown in shallow troughs for larger quantities and since it requires different inputs should be remote from the AP system. Concrete is usually used for trough construction(to provide steady buffering), a paddle wheel(solar as it is low energy) to keep algae at all layers moving so they don't die off. The shallow depth means less volume water used compared to aquariums. Finally the basic inputs below

Fertilizer g/l

Sodium carbonate (soda ash) 5

Sodium chloride, crude 5

Potassium nitrate 2

Sodium bicarbonate 1

Potassium sulfate, crystallized 1

Urea 0.02

Monoammonium Phosphate, crystallized 0.1

Magnesium sulfate, crystallized, (7 H2O) 0.2

Lime 0.02

Ferrous sulfate 0.005


Since SP is grown in high temps, growing outside of tropical locations will demand higher heating and energy cost. I feel we can design a working model to be used to calculate SP output and provide building plans listing  building plans, hardware items and chemical inputs, an entire SP manual designed for AP. Manual 1 for 20 fish, Manual 2 for 40 fish and so on.


I really have not had the time to make any progress on the algae growing myself yet and it will be a while before I do I expect so I hope others can take the lead on it.

So keep up the good work on reporting info and ideas on this Harold.

Why couldn't you grow the algae in your FT?

After all, that's what Tilapia eat in their natural habitat, right?

Hi Ronald,

The algae being discussed on this topic is Spirulina. For SP production to be possible we have to create a particular environment. The right type of water movement and depth, specific PH, particular temperatures and sunlight, and the right mix of nutrient are some of the underlying factors necessary for SP production. Because the conditions in the FT do not match exactly the conditions required for SP production, the growth will be poor at best and other types of algae more suitably adapted to these conditions can eventually dominate and overtake SP. Growing algae in the FT can also rob system oxygen and become a detriment or outright hazard to your AP.

There are methods of green water culture that can be used for growing Tilapia but they are generally not all that compatible with Aquaponics directly.  At least if you are trying to grow veggies from your aquaponics.  But that would probably be more appropriate to a new discussion.


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