New Anoxic Experiment - The Missing Key?

[@dusk1947]

To get technical. In ecological terms, what you're dealing with is the 'carrying capacity' of the bacterial population in your closed system. Carrying capacity (K) is the number of individuals the environment (your tank) can support indefinitely. By adding a 'food' source which addresses their limiting rate for growth (Carbon), you can artificially increase the population density. And then, potentially, create enough stratified layers of bacterial colonization that they use up all the free oxygen in the sediment. Forcing those at the bottom to undergo Denitrification. However, this process has trade off's. First, it adds extra materials and labor on your part to maintain it. Second, your population target is moving. You're going to build a population that will crash if you stop artificially providing its carbon source. And if you're successful, you may find other elements become a limiting factor. At which point, your population stagnates, and you're overdosing organic carbon sources which will foul the water. You will also feed the free-floating and surface films of heterotrophic bacteria in addition to the facultative anaerobes you're targeting. So, you may get some odd bacterial blooms and have no way of easily dealing with them other than a water changes. (Marine systems use a protein skimmer for this function). It's fun to see you go through this, with as much detail and effort you've shown. But, you're hitting the point where practical application becomes questionable. This is a more 'advanced' area of the hobby due to the added effort and variables. However, the marine side of the hobby at several points really embraced carbon dosing, and moved away from things like simple sugars, vodka, and vinegar due to the difficulty of regulating it over a long period. There are several specific products which are now formulated for marine bacteria's for this purpose, which are either a dosed liquid or a solid pellet for a reactor (a bio-pellet). They also moved away from the deep sand bed and denitrification as the goal. And instead found focusing on carbon dosing the aerobic heterotrophs; the bio-films that grow and slough-off bio-pellets (much like in a moving bed filter) or feeding the free floating bacteria and surface films; which take up excess N & P through their growth. Both of which are skimmed out of the water by a protein skimmer as a nutrient export, removing the excess bacterial population from the water and lowering N & P. This change happened over multiple years, mostly due to the difficulty of regulating and maintaing that deep sediment layer. You also don't need this process if you have abundant plant life. The marine side did it, because most of our corals come from oligotrophic conditions with very low inorganic P & N. Elevated levels in a marine system typically create horrific algal blooms. Where as, keeping aquatic plants simply uptake those and compete with algae on the freshwater side. What you're trying now can work. Just not easily. And best of luck maintaining it over months or years. Regardless, it's interesting see you progress through this topic.

[@fownine4life853]

U really sound like a smart cookie, but for my understanding of what you said, in layman's terms, the anoxic system wont wrk over time, correct?

[@christiancalkins9372]

All great points. I think Bentley’s mission here is to see if denitrification with this system is possible in theory, to at least get that doubt out of the public consciousness. From there, practical application is certainly another conversation, but it’s a start. You’re right in that if Bentley goes through with this dosing with vodka rather than relying on the organic carbon in a regular aquarium setting, the bacterial population will crash when he goes to plant the tank and put fish in. This is why I suggested the use of fish and leaf litter, where the dosing is practical to normal aquarium applications, and as the leaves decompose, the carbon dosage would (to a point) be progressive over time. I think specificity matters here, and dosing vodka might prove something can work in theory, but not in practice. That would have to take place in a completely separate experiment, I suppose. Lots to think about. Great input!

[@dusk1947]

@@fownine4life853 it's very difficult to keep it working over time, yes. His anoxic experiment in all likelihood has ended. His system didn't produce denitrification at a 'normal' level of input. Nor did it for many others who have tried it, including myself a few years back. Carbon dosing, is the next step to try and create those conditions with extra inputs, but it's at a level beyond what a normal aquarium would have. Bentley is exploring a niche which isn't used commonly in freshwater systems. And isn't needed in particular if you have abundant plant life. However, it's well explored in other fields, and has been used by other forms of aquariums for years (where plants aren't common) which lead to the development of more reliable methods. As he mentioned, carbon dosing reef system is very common and well understood. And they intentionally moved away from what Bentley is about to try, because it's so hard to regulate or balance over the long term. Hobbiest's have gotten this to work through carbon dosing. But, because it's a living system, it's a delicate balance. And I'm not really trying to 'sound smart', I'm just using some of the scientific concepts behind what he's doing. They may be uncommon terms in freshwater aquaria, but using and hearing the terminology over time can make it more common. Too many in the hobby consider topics like this to be some kind of secret or mystery. They're not. It's just explored in very dry technical papers and journals, or in obscure 20-year old hobby forums, and in a vocabulary most people aren't used to (biology). I think what Bentley's exploring here is great, his design is pretty descent, he's transparent, and entertaining. But quite a few already know where it's headed. And I'm just trying to provide context about where others have already gone with this same topic in the hobby.

[@BentleyPascoe]

@@christiancalkins9372 if you have some spare time, please email me: [e-mail] I'd like to pick your brain a bit!

[@superaquatics]

Hi Bentley. Thank you for keeping an open mind and continuing the experiment objectively and going ahead with the carbon dosing. I wasn't sure about the dosing of vodka and was afraid of harming the fish with the alcohol so I dosed with sugar as I thought it safer for the fish in case of any excess. I did not follow any specific dosing regimen and just added a quarter of a teaspoon to the filter per week for a couple of weeks for my 50g tank just to kickstart the denitrification. There was a slight increase in ammonia initially but then it stabilized and cleared then the nitrates also started coming down so I stopped dosing further. I also added some bacteria capsules to the filter. I have never looked back since as my nitrates are barely detectable and a no longer need to do weekly water changes apart from top offs and once a month to replace minerals. I have zero plants since goldfish destroy the plants. Keep updating as I would like to follow the course of your experiment. 👏👏👍

[@authmal]

I think there are a lot of people in this hobby that absolutely think there's only one way to possibly do things. They're usually wrong, but that won't stop them from trying to shame others for doing things differently.

[@BentleyPascoe]

@@authmal there's many ways to solve any given problem

[@UncleSmileys.Aquariums]

The problem with vodka is I would end up dossing myself.

[@jeffkane4391]

I'm interested to see the outcome of round 2. Thanks for the update 😊

[@razinfishes1918]

Bentley lol you are so smart about all this very technical detailed analysis now my brain hurts more. One day I might get as smart as you are. But at my age I'm not thinking that's going to happen. You do a great job at explaining all this stuff

[@nabokovfan87]

@4:30 Three future tank goals, all 60 breeders. A. 100+ corydoras B. 300+ amano shrimp, preferably bred by me C. Just a massive tank with 30-50 SAEs being fun.

[@rldickie]

I ran an unintentional and unscientific experiment on my tank this Summer. I got sick and neglected it. No filter or heater topped up when the water hit the halfway point. Fed 3or4 times. My magnificent crop of hair algae died and so did half my fish and most of my snails😢. Duckweed came back and my plants exploded, some now growing out of the water, and the shrimp all thriving. I'm better now and so is my treatment of my aquarium. My new pepper corys seem healthy and happy and I'll never do that again. I guess I kinda went off, but I think this was an interesting aquatic experience that I just wanted to share. Oh yeah, and it looks like anoxic stuff is starting to happen in the substrate.

[@wildbill4138]

Very interesting Bentley..

[@ezwaters5847]

My understanding of asimilatory denitrification is in addition to plants, various bacteria, fungi, substrates etc can also assimilate Nitrates.

[@Whips_World]

Hey! How about that. Normally when I listen to learnin' shtuff, all I hear is Charlie Brown's teacher's voice. I was actually awake and understanding what you were talking about here... mostly.

[@BentleyPascoe]

@@Whips_World "mostly" 🤣 thanks Whip!

[@ivandragomiloff2356]

Is nitrate really that bad? Doesn’t it take large amounts to be harmful to fish? Seems like aquarists are chasing nitrate numbers, that are unnecessary.

[@javieralegremoreno2998]

Carbohydrates (C and H)+ Oxigen (from NO3)--> CO2 + H2O +N2 They burn carbohydrates just like us. And you can't burn CO2, is already 🔥ed (oxidized)

[@javieralegremoreno2998]

Anoxic bacteria breath nitrate, because they don't have oxygen available wherethey live. Butt they need carbon based FOOD just like us. CO2 is not FOOD, just like we can't sustain our selfs on it. And carbon hardness neither. Needs a carbon based food with energy like sugar alcohol or any other carbohydrates easy to digest.

[@javieralegremoreno2998]

CO2 + NO3--> There is no energy. Everything is already oxidized.

[@javieralegremoreno2998]

Try to feed for self with CO2, is not a very good idea... And CO2 reactors from reef aquariums doesn't have any thing to do with denitrification🤦

[@majorbruster5916]

Carbohydrates consist of C + H + O, empirical formula Cx(H2O)y. Nitrifying bacteria use NH3 and NO2 as their energy substrate to form Carbohydrates, in the presence of oxygen. This is an aerobic process. Denitrifying bacteria utilise NO3 as an energy source, breaking the molecules to access the oxidised oxygen. They need an organic source of carbon and hydrogen to build carbohydrates in the cell, which they would usually get from the breakdown of organic matter such as leaves. Their activity releases tannins and humins, which are organic sources of carbon and hydrogen. Ethyl alcohol (C2H5OH) and methanol (CH3OH) are easily available sources of organic carbon, whose molecules are easily broken down.

[@damiangrouse4564]

How can you tell if you add too much vodka? Some of the male guppies will have black eyes, missing teeth and there’ll be a tiger barb in the filter

[@Sec_coach]

No lol this method is well known

[@BentleyPascoe]

@@damiangrouse4564 🤣

[@wcdeich4]

Good luck. Reef keepers told me cleaning my apartment w/ alcohol may have amounted to accidental carbon dosing & contributed to why I get the dreaded white slime. It would be interesting to see if your tank gets think white slime. I tragically & accidentally killed my fish when I was spraying an insecticide in my apartment (long sad story I do not want to talk about). So I'm taking a break from fish. If ever try again, I think I will try a few male guppies w/ a bare bottom tank & just clean it every day.

[@AmazonasBiotop]

Great decision. When starting with vodka you will probably get a spike in NH3 that goes down again. (When bacteria will brake down ALSO some of the NO3 to NH3 and the cycle for the NH3 repeat.😢) So it is good that you dont put fish in there and start to also measure NH3 so that gets documented and noted. I guess that here its good to use a dosing pump if doing this continuous.🎉

[@anthonyruth5606]

Dried leaves driftwood are a good source of carbon I’m a gardener and I use the lasagna method u stack brown leaves wood dried out lawn clippings and then u stack green material for the nitrogen to feed the plants the brown material material is for bacteria bc we need bacteria to convert the carbon into available nutrients for the plants to consume

[@uzyh7622]

Charcoal is good to raise the carbon level ???

[@beerprem]

In a sw aquarium you dose carbon to feed aerobic bacteria that you then remove with the nitrate in a skimmer.the denitrifiers do lower dissolved oxygen levels though so it may help kickstart your anaerobes into action. I would still put money on it being a miserable failure though. If it does work id love to see a side by side plant v anoxic denitrifcation battle.

[@BentleyPascoe]

@@beerprem I honestly don't think it is possible for an anoxic system in such a small tank to compete with the density of plants that you can put in there. Assimilatory denitrification the way that plants do it is one of the most efficient things in nature as far as our hobby is concerned.

[@AlohaAloha808]

Have you been measuring Oxygen levels to determine if anoxic conditions even exist?

[@John-Ebsen]

But bourbon adds tannins so extra beneficial!

[@rldickie]

Single malt Scotch for me and my fish. Lowland, lots of peat.

[@spyrit35]

There seems to be some serious aversion here to fish food... fish food is something I can relate to, I can relate to 12 pellets of ciclid gold per day... I dont even need fish to be in there, you could feed a stocking in the water column to make it cleaner and I wouldn't care... I'm sorry, a test on vodka is just something I cant relate to because I've never fed fish vodka and I dont know how many ml's of vodka I'd feed 6 messy bristlenose pleco's (just as an example).... I'm out on this one.

[@Merb34st]

Alcohol denitrates? Sweet, imma live to 100

[@vb2377]

Do testing on fish food. No one has done it empirically.

[@BentleyPascoe]

@@vb2377 how would you empirically test it? Beyond getting guaranteed analysis, I don't think my meager arsenal of testing would be set for food products.

[@vb2377]

I think the only way is via weight

[@Sec_coach]

😂😂you guys are still doing this