Backyard Aquaponics
A place to discuss aquaponics

I think this has branched into a very interesting discussion now.

I've never seen aeroponics, I'm assuming the hydropic method of having roots suspended in a mist, used in an aquaponics setup. Can we some how tabulate these methods as listed by Stuart and Sleepe along with dagrams or pictures of each setup so we can move towards a standardized jargon, even if only in the forum. Then we can move towards practical experiments on each

ok im going to try to clear the air with my understanding of aerobic/anaerobic/anoxic. note there is a big difference between anaerobic and anoxic. firstly aerobic digestion is the process which efficiently converts ammonia to nitrites them to nitrates. seeing that this process actually oxidize the ammonia in both cases we can see why it is favors oxygen rich environment. simultaneously the process also utilize carbon dioxide for cellular growth and so on and hence producing H+ ions as a byproduct. The big disadvantage of this process is the rapid decrease in pH over time which can cause your system ecology to crash simply because this process indirectly utilize Carbonate in the form of CaCO3 by combining with the free H+ ion and hence releases more CO2 gas for the bacteria to feed on. This is why water hardness decreases over time. from this process we see that aerobic bacteria mainly uses dissolved substance ammonia/ carbon dioxide as energy sources therefore most of the carbon locked away in the fish waste isn't broken down at a significant rate simply because there are surplus 'food' for the bacteria already in the water. Therefore all the minerals thats locked away in it organic form is the fish waste isn't fully utilize because the bacteria needs to exert more energy to get the same growth. and here is where we go to anaerobic decomposition. im tired I'll write the rest later. views and inputs are encouraged.





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Intriguing stuff. I'm afraid I;ve never heard of anoxic digestion :/

Anoxic translates to toxic, to be avoided. It is a slippery slope from anaerobic to anoxic. A well balanced system will actually have some minimal anaerobic zones. An RSG filter purposely creates an anaerobic zone. The important thing is to make sure the hydrogen sulfide that is produces does not get to levels harmful to fish. Popular belief is that hydrogen sulfide should be avoided at all costs, but in reality a little is actually good for plants. The trick is to make sure it is off gassed before it reaches the fish.

Anaerobic digestion, dissolved O2 <1mg/l on average. People usually shy away from this type and wants nothing to do with it especially when it pertaining to aquaculture/ aquaponics. Some say that ‘ anaerobic pockets’ within a system can cause spikes in ammonia and even decrease the ability to create nitrates. They are partially correct, but I’m not going too in-depth into the biology. Anaerobic bacteria unlike aerobic bacteria favors oxygen-less atmosphere, mind you is they are exposed to air they do not die but simply mimics aerobic bacteria. The disadvantages is that they are very inefficient when compared to aerobic;  it’s like ( don’t quote me) 1million anerobic bacteria is needed to do the same work as 1 aerobic bacteria. We may wonder then why should we even need it, best we keep it out our system to begin with. But the advantage of anaerobic bacteria is limitless to put it simply. First of all they utilize organic carbon, you know the ones thats bounded to proteins and other matter in the fish waste, so by using this type of carbon the bacteria is forces to reduce the protein links and hence releasing the stored minerals. But we see this as a rise in Ammonia simply because this was the locked away unutilized orgainic nitrogen within the fish waste and thats why we see a spike in ammonia because if we keep our feeding rate steady the bacteria in the system has already formed to use all the ammonia produced from the fish at feeding. But now we have another ammonia input from the decomposing fish matter in the anaerobic areas. So well this leaves your system to undergo a micro cycling once more because of this, but is extremely worth it cause of all the minerals released into the water, especially phosphorous, potassium. For more information research waste water treatment.

Secondly, the next big advantage of Anaerobic process is the conversion of excess nitrates to nitrogen gas. We should be encouraged to do so mainly for the reason of pH control. People normally says that anaerobic regions increases your overall pH, and sometimes goes as far to say that the pH will continuously increase till bout lest say pH8. They are wrong in a way. The byproducts  of anaerobic digestion are actually organic acids suce as acetic acid and latic acids alcohols and so on. But the in the process of denitrification nitrates are reduced to nitrites then to nitrous oxide then to nitrogen gas.

NOTE: NITRITE is never converted backed to AMMONIA and can never be I believe.

In this process all the carbonates that was utilized to produce nitrates is recovered and basically a well designed system can balance the conversion to all maintain pH at 7 without adding buffing agents. By reducing nitrates; this favour fruiting plants such as tomatoes and so on. But i must warn you, now we got to process within the system producing Nitrites so your Nitrite level will peak and hence i said well designed system. Now to anoxic. Anoxic digestion is where everything goes downhill.

Anoxic digestion dissolved oxygen = 0ppm, dissolved nitrates = 0ppm. Reason i put in nitrates also is because not living organism cannot survive without “O” aerobic bacteria gets their “O” from air as O2 or oxygen. Anerobic bacteria gets their “O” from mainly Nitrates/Nitrites (NO3/NO2). But when nitrates and oxygen hits 0ppm this is when the stink smell begin. Basically the bacteria is forced to utilize the “O” from sulphates(SO4) and from ferrous oxide(FE2 O3). The byproducts is the nasty smell of hydrogen sulphide or H2S. And thats why when after a certain thickness of solids collect at the base of a RFF it starts to stink because O2 nor NO3 is not able to diffuse into the layer fast enough to feed the bacteria. So they use the next best thing. But if u can design your filter well u can be able to utilize the benefits of both aerobic/ anaerobic digestion together with mechanical filtration all in one filter. Rate comment.



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+1 cookie

I agree with the idea that a well designed filter can handle all aspects of digestion. This is why I'll be putting two home made moving bed filters into my filter tank to keep drawing up the waste from the bottom and letting it mineralize to the max in the system before solids are removed for the pots. The UVI concept of adding orchard netting to sedimentation tanks so as to promote de nitrification is also very interesting research; it also supports the fact that controlled small anaerobic areas are actually beneficial if used in the correct way and for the correct plants.

If I was home to maintain the system myself I'd do it but I want to minimize the things mom has to do.

coming to my view concering if to leave solids in the system, I highly support leaving solids in the system. but I strongly suggest confining the solids into one localized area especially if u in to DWC GB simply because these floating debris clings to roots and cause bacterial film build up. but solid retention in my view is important but I not sure the length of time to leave it. right now I'm experimenting on how long its able to stay. I'm going on a month so far.

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Very nice Cookie

There is one step however that appears missing in the reduction or depletion and that is the archaea and the production of methane. I may have missed it and I apologise if I have done so.

Abdul my listing of plant grow methods was based on my opinion of speed of growth and not necessarily practicality for AP. Some may consider bubbler buckets to be DWC but I have always considered them to be a hybrid of aeroponics and DWC (unless you have some really flash DWC setup) .

no need to apologies Sleepe I actually left it out simply because I felt it not really relevant to the topic at hand. its more interms of energy efficiency but u are absolutely correct.

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Cookie, (Expecting you probably already know this one but putting it out for further public discussion)
I think many have found it works well to at least temporarily remove excessive solids from the circulation of the aquaponics system into a digestion tank or pond (basically flush your solids filter into a tank or bed where you can bubble the heck out of it for a time until it is "stabilized" basically meaning the "stink" has been bubbled away. Yes I know I'm not necessarily using correct terms here but I think people will get my meaning. Then the aeration can be turned off and the sediment allowed to settle and the clear very nutrient rich liquid can be introduced back into the system if desired while the sediment can be removed and de-watered and used for soil fertilization or compost or worm bins (worms really love this stuff) etc. (I've actually heard of some operations selling the nutrient rich water from the digestion tank for higher prices than the veggies!!!!! Gardeners actually bring their own jugs and pay quite a bit for the liquid fertilizer. Other places sell the dried sludge as nutrient rich soil amendment.)

aka - Nitrification. I would probably have called this aerobic respiration not digestion but it's been a while since Microbiology class (also would have been anaerobic respiration for your other post). Not bad but a bit misleading since other reactions besides Nitrification would fall into this category as well. Probably would have been better to say that Nitrification is a form of aerobic digestion (or aerobic respiration)

Some of the types of bacteria involved
Aerobic respiration
Hydrogen bacteria
Iron bacteria
Sulfur bacteria
Nitrifying bacteria - Nitrosomonas, Nitrobacter, Nitrospira...

Anaerobic respiration
Denitrifiers
Methane Bacteria
others

Thats a bit picky scotty since there is an additional oxygen molecule added at each step.

Cookie

I was only really interested because, and here comes a confession, I have a top pond (about 4'x3' by about 2.5' at its lowest point). It is fed by a waterfall and is filled with sludge; so highly oxygenated water runs over the top and down the stream. Regularly bubbles surface and although I have not tried to light them they are not rotten egg gas.

The other reason is I work at a landfill site.

interesting posts

now...

Cookie vs Stuart. Topic: solids removal.

Go

just kidding

In the interest of accuracy that probably should have been an oxygen atom added to the molecule etc; I was doing my shopping list at the time which is always a more interesting subject.

I don't believe you.