Backyard Aquaponics
A place to discuss aquaponics

AA- no medium in the net pots. They plant their seeds in dirt trays in the shed with lights, then wash the dirt off each seedling and plant into the net pots. They have just realised this is labour intensive and will now start planting the seeds in small abounts of coir which has no effect on ph and can be composted, and they are going to look at doing this straight into the rafts I think when they have more poly houses.

VB, I reckon you have a very solid point there. I took with a pinch of salt all comments re talapia (as I did for their profit figures- too many variables re our conditions and theirs), as I feel they stock soo heavily and only feed a 32% protein diet, solids will have to have a different composition. Could have a bit to do with their clogging gravel too??

AA - at Minnamurra they are doing continuous cropping normally, harvesting one bed each week over a 4 week period. In VI they certainly do continuous cropping.

Thanks VB.

There are too many variables to expect their results yes, but you should get great results regardless with this place on tap.

Was their beds really 500 deep? Thats madness for lettuce etc.

Wilson told VB 500 mm , but from my observations and photos (i never actually got out a tape and measured them, that would have been a bit obvious ), they were closer to 300mm, esp when you take into account the polystyrene rafts float on top of the water.

Stu

yeh, looking at a ruler 300mm would have been generous

Pays to be suspicious at times thanks guys.

On clogging vs diet - A higher protein diet increases nutrient content in the waste I do not think a lower (33%) protein diet makes gelatinous faeces or I'd have seen this from 33 percent feeding comets, golds, orandos...

Never heard of it being Tilapia specific either.

I think the scientists root zones were endangered as systems got warmer as water is barely moving in there. The BOD was adequate for the lettuce etc then the floaters arrived, not enough oxygen, problems...

Increasing the flow in DWC has several advantages.

Better oxygen replenishment.
Less filamentous type algae.
Prevents excessive floc build up.
Allows breakdown of solids.
Nutrient access more constant for plants.
Better for your fish.
Can be utilised for cooling and heating.

There's probably more.

Downsides

More evaporation.
More humidity.
More power.

There's probably more.

Cool, it was only a guess re the protein content

Nutritional value of your bio-film.

Extensive testing of stream beds has been done both here and offshore in order to 'follow the food chain'.

Leaf waste was thought to be a key ingredient and responsible for much of the nutrition. Streams had this leaf matter removed with netting placed over the tops of the streams to stop new leaf matter entering the waterbody.

What they found surprised them. It was quickly apparent there was no marked difference in the nutritive value of invertabrates caught from debris free, and leaf littered streams. Though eventually it would alter what insect populations and bacterial percentages were found there.

The major nutritive value in the insects and other life forms diet was coming from the biofilm itself. In streams where leaf matter was eaten the main nutritional component was the bacteria colonised on the leaves...


We've learned that grazing your bio-film is good for it, and this in turn is good for your system.

But how do you find grazers for your Aquaponics system?

They're already in there.

Omnivorous fish will eat leaf matter but prefer many foods blanched first. ie: silverbeet, parsley, spinach. What I do is throw these veggies in fresh. They will just float around 4 or 5 days and collect bacteria as they do. Just when you think it's gone rotten, and the fish won't want it - they gobble it all up.

This whole process has many benefits.

I don't have to cook for my fish.
I get to add iron the easy way.
The bio-film gets to fluctuate being both enlarged and grazed upon in this process.
Proteins are cycled into the system.

Polyculture with algae eaters will help regulate your bio-film even further.

A problem with existing research.

Robert Koch made one of the most important breakthroughs in the history of microbiology with his discovery of methods for the production of solid nutrient media, and the ability to isolate pure cultures of microorganisms.

The importance of this discovery to advances in medical, agricultural and industrial microbiology would be hard to overestimate. The dividends these techniques returned have positively affected the lives of nearly everyone on the planet.

The training of generations of microbiologists has been based, to a significant degree, on the investigation of the properties of pure cultures - one at a time. As productive as this strategy has been it perpetuates an astonishingly inaccurate conception. In fact, pure cultures are absent or virtually so in nature.

Most of what we know about microorganisms has been learned under conditions that exist nowhere outside of a laboratory.

Microorganisms, like other organisms, exist in communities in which a myriad of interactions exist.

Yeah, if the microorganism is symbiotic with another, isolating it isnt really going to tell you much about the potential of the two, and what the individual one really does.

That's it. Like Aquaponics. Hydro works well, so does Aquaculture, but the sum of the parts together makes for superior growth and efficiency.

We'll look at how the bio-film is formed next, I got work to do outside first...

I'll be looking forward to the next installment, but in the mean time i have more gravel to wash

Abridged and edited from study. A Biofilm Primer. Author Unknown. And Wikipedia.

What are bio-films?

Biofilms are populations of microorganisms adhering to environmental surfaces. They are usually encased in an extracellular polysaccharide* that they themselves synthesize. Biofilms may be found on essentially any environmental surface in which sufficient moisture is present. Their development is most rapid in flowing systems where adequate nutrients are available.

Biofilms may form:

1. on solid substrates in contact with moisture.
2. on soft tissue surfaces in living organisms.
3. at liquid air interfaces.

Plant tissues also commonly have microbial populations associated with their external tissues.

One such plant microbe association is called the rhizosphere.

Rhizosphere is a relationship between the plant roots and root hairs and a complex microbial community. The rhizosphere association is mutualistic. Plant roots secrete significant amounts of sugars, amino acids, vitamins and plant hormones which vastly stimulate microbial growth in the immediate vicinity of the root. This microbial population in turn facilitates the absorption of nutrients by the plant from the soil/substrate/water stream.

How do biofilms form?

The formation of biofilm is not a random process. It follows a course the nature of which can be predicted and recorded.

Within minutes, an organic monolayer adsorbs to the surface of substrate. This changes the chemical and physical properties of the substrate. These organic compounds are found to be polysaccharides or glycoproteins.** These adsorbed materials condition surfaces and appear to increase the probability of the attachment of planktonic bacteria.

Free floating or planktonic bacteria encounter the conditioned surface and form a reversible, sometimes transient attachment often within minutes.

This attachment called adsorption is influenced by electrical charges carried on the bacteria, by Van der Waals forces and by electrostatic attraction. The precise nature of interaction is still a matter of intense debate.

If the association between bacterium and substrate persists long enough, other chemical and physical structures may form which transform the reversible adsorption to a permanent and essentially irreversible attachment.

The final stage in the irreversible adhesion of a cell to an environmental surface is associated with the production of extracellular polymer*** substances or EPS. Most of the EPS of biofilms are polymers containing sugars.

This layer of EPS and bacteria can now entrap particulate materials such as clay, organic materials, dead cells and precipitated minerals adding to the bulk and diversity of the biofilm habitat. This growing biofilm can now serve as the focus for the attachment and growth of other organisms increasing the biological diversity of the community.

The microbial inhabitants within biofilms in a significant sense behave as multicellular assemblages. Far from being the homogeneous populations usually assumed in planktonic pure cultures. Biofilms as simple as colonies on agar surfaces and as complex as bacterial populations inhabiting the flora, fauna and entire submerged workings of an Aquaponic system, behave in many respects like the tissues of a multicellular organism.

Multicellular organisms are those organisms consisting of more than one cell, and having differentiated cells that perform specialized functions. Most life that can be seen with the naked eye is multicellular, as are all animals and plants.

Here's food for thought then

When a biofilm is first starting out - the first layer, that eventually becomes entrapped in irreversible film, can be polysaccharides OR glycoproteins. One a complex carbohydrate, the other, protein and carbohydrate. You WANT both. Without both, your bio-film will not function as well as it could in providing food for varied planktonic life, rhizosphere interaction, and assisting in disease resistance for plants, animals, and the bio-film itself.

Good news! Ensuring this happens is easy.

Immediately you get your system filled up add some bacteria from a tank containing healthy omnivores.

Variety is the spice of life.

* complex carbohydrates - starch, glycogen, cellulose & chitin (part of algae walls) are some examples of polysaccharides. Extracellular, very basically, they are linked together.

** Macromolecules are composed of a protein and a carbohydrate. Some of these are antibodies, responsible for boosting immune systems. Nice to know with all these fish we grow.

*** Molecules consisting of structural units and a large number of repeating units connected by chemical bonds.

Nice info AA....