Self-Sustaining Tank???

[Flear]

i'm reminded as i sit here (i forget this too often - because i'm using an air bubbler)
i'm not going to rule out the need for emersed plants,

CO2, a gas, ... gassed off, is no longer available to plants, ... removing carbon from the system

Ammonia, a gass, ... similar to CO2

there's ways around these (both)

azolla has a symbiotic cyanobacteria that can reintroduce nitrogen into forms the plants can use

emersed plants can get CO2 from the air and in turn move this into the tank

 

[Caliban07]

Hello D...

I've kept medium to large tanks for several years that only need water replaced due to evaporation. A gallon or so a week per tank. You simply submerge the roots of certain land plants and the roots take in all the forms of nitrogen produced by the fish.

B

I thought TDS rises if you just top of evaporated water?

Do the plants handle these too?

 

[GodFan]

So I dont knos anything about the sulfur. In theory the soil should add it back. My africa leaf fish setup has no emmersed plants and is very near if not self sustaining (I do have to feed them). I have crypt, anubias, java moss, and java fern in it. A variety of plants helps absorb all nutrients.
As far as TDS. It is a tough one. I think something will use it since you have stagnant water systems in nature. My leaf fish are ok but I dont know what level the TDS is at. Some fish arent bkthered by TDS much either. At this point I am wondering if TDS is abeorbed by emmersed plants though..

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[aqua_chem]

As I rule, I'm extremely critical of this concept. It's much more complicated than people take it to be, and I've only seen it executed well a few times.

As far as TDS goes, topping off with tap water will add to your TDS by increasing your mineral content, but it also adds essential bases to keep your water buffered. It's an interesting give/take relationship that should be addressed. In nature, rain (essentially distilled water) will do a lot of this for you, even adding bases in the form of bicarbonate from underwater limestone. It's a magnificent but complicated relationship that I sadly don't understand as well as I would like.

The emersed plants also present another challenge. They have an infinite supply of CO2 from the atmosphere, so they are generally limited by nutrients or light, unlike aquatic plants that are generally limited by CO2 (which is usually in short supply). This allows them much greater up take of nitrogenous waste. However, this creates another problem you've already encountered: non-nitrogenous nutrients, particularly micronutrients like iron that aren't in great supply, or are in relatively short supply compared to nitrogen. All the iron/Mn/Zinc/whatever is taken up by plants is sequestered in leaves, unavailable to the ecosystem (note:this is also a mechanism by which the foodchain will often fail in tanks like this except with macronutrients, if they get that far). Your plants keep trying to absorb nitrogen, because heck, why not with all that CO2 and light, but end up making deformed/deficient leaves as a result of massive deficiency. We also see this in planted tanks when CO2 is added to a tank without an appropriate increase in nutrient dosage.

sadly i have not followed it in 9 months or so ... last i heard a g/f started feeding the fish and he commened about how he could no longer call it 'self-sustaining

Instant No Button! Star Wars funnies FTW!

 

[Caliban07]

As I rule, I'm extremely critical of this concept. It's much more complicated than people take it to be, and I've only seen it executed well a few times.

As far as TDS goes, topping off with tap water will add to your TDS by increasing your mineral content, but it also adds essential bases to keep your water buffered. It's an interesting give/take relationship that should be addressed. In nature, rain (essentially distilled water) will do a lot of this for you, even adding bases in the form of bicarbonate from underwater limestone. It's a magnificent but complicated relationship that I sadly don't understand as well as I would like.

The emersed plants also present another challenge. They have an infinite supply of CO2 from the atmosphere, so they are generally limited by nutrients or light, unlike aquatic plants that are generally limited by CO2 (which is usually in short supply). This allows them much greater up take of nitrogenous waste. However, this creates another problem you've already encountered: non-nitrogenous nutrients, particularly micronutrients like iron that aren't in great supply, or are in relatively short supply compared to nitrogen. All the iron/Mn/Zinc/whatever is taken up by plants is sequestered in leaves, unavailable to the ecosystem (note:this is also a mechanism by which the foodchain will often fail in tanks like this except with macronutrients, if they get that far). Your plants keep trying to absorb nitrogen, because heck, why not with all that CO2 and light, but end up making deformed/deficient leaves as a result of massive deficiency. We also see this in planted tanks when CO2 is added to a tank without an appropriate increase in nutrient dosage.





Instant No Button! Star Wars funnies FTW!

A couple of my plants were looking a bit worse for wear. I did a 25% water change and within a day they had perked up. Almost turned green again. This would suggest to me that the nutrients that were added in the water change were needed.

Off topic slightly, what is a good liquid macro/micro nutrient product I can add to help the plants?

 

[GodFan]

A couple of my plants were looking a bit worse for wear. I did a 25% water change and within a day they had perked up. Almost turned green again. This would suggest to me that the nutrients that were added in the water change were needed.

Off topic slightly, what is a good liquid macro/micro nutrient product I can add to help the plants?

Yes my experience has been the same. Plants perk up with top offs or water changes.
Tbe point of a sustainabke tank is to not have to add anything like ferts. Maybe your plants are not right for this setup? Seachem makes good products I here though.

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[Caliban07]

Yes my experience has been the same. Plants perk up with top offs or water changes.
Tbe point of a sustainabke tank is to not have to add anything like ferts. Maybe your plants are not right for this setup? Seachem makes good products I here though.

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Thanks godfan.

My setup is just that of a normal tank. I'm not actually trying to attempt a self sustaining tank. They are just general plants like Anubis, elodea and cobomba. Seachem have a few different ones I'm just wondering which was the best.

 

[GodFan]

Thanks godfan.

My setup is just that of a normal tank. I'm not actually trying to attempt a self sustaining tank. They are just general plants like Anubis, elodea and cobomba. Seachem have a few different ones I'm just wondering which was the best.

Oh ok
Sorry I cant really help their. I pick plants that dont need any additives because I dont have the time to keep up with all that.

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[Flear]

plants pose their own problem for a self-sustaining tank

they eat nutrients, ... and don't give them up till they die.

stem plants grow up, and continue growing up till they reach the surface, fold and bend and curve around the surface till they have created an island of sorts that with it's boyancy will allow the plants to continue growing up and become emersed.
(experience)
-some will have strong enough stocks to grow straight up and out of the water.

but plants are still a nutrient sink, if nothing is doing anything to break your plants down, your substrate must continue to have nutrients that your plants can continue to use to grow with, ... eventually your substrate will run out, or run into deficiencies and your plants will experience those deficiencies as well.

what is being done to ensure your plants reach a balance of new growth and removing older growth, or new growth keeping up with new growth being eaten without the tips being removed to a point the plant stops growing, old leaves will last only so long before lack of light, age, nutrient issues, critters, ... turn an old leaf into detritus (and return those nutrients to the water column)

the plants will grow faster than old leaves are lost due to nothing other than being old leaves, if this is not the case, there's seriously something wrong

---

as a requirement you need something to eat or otherwise break down the plants at a rate the plants can continue growing to compensate for, ... a tug-of-war. ...

the plants will kill themselves over time given enough time as they will starve themselves to death

without the plants your fish would pollute the water and kill themselves

one letting the other reign unchecked will kill both

fish eating too fast, ... fish win, then fish die
fish eating too slow, plants win, then plants die, then fish die

---

most plants in the hobby i have noticed are gotten to fill a tank
most fish in the hobby that would eat plants at all are gotten with the warning that they'll eat your plants, so best get X plants that the fish won't touch (for whatever reason)

there's very little that is mentioned as "this fish will eat these plants" just blanket statements of "don't get plants with this fish" (anubias & Java fern being the only "safe" plants to get)

 

[Flear]

liquid aquarium fertilizers add nutrients to the water column

not the substrate

fish poop, and that will filter down into the substrate, that will break down due to bacterial activity, ... as the detritus breaks down nutrients are available for plants to take in through their roots

fertilizing the water column, plants will absorb through their leaves.

nutrients in the substrate to be broken down into forms available for plants, ... requires deeper substrates.

and this gets people scared

some nutrients can be processed from detritus into nutrients the plants can used with aerobic areas in the substrate (everything in the substrate that has access to abundant oxygen)

some nutrients can only go so far and bacteria will only process it so far because energy from processing those nutrients isn't efficient and the bacteria will process other nutrients

... so there's a bunch of nutrients that will accumulate in the substrate that cannot be processed unless the environment in the substrate changes to a point that processing these nutrients become a do-or-die situation for the bacteria.

these sections nutrient turn-around is very slow, there's not a lot of energy gained in processessing these nutrients, the bacteria here for all intents and purposes are slower.

and this happens in the lower areas of the substrate where free oxygen is either limited or completely lacking.

and people worry about H2S, ... which in moderation is where you're getting your sulfur for your plants. (this is one of those i'm familiar with that requires this anoxic zone to be processed), ... yes it's a very toxic combustable gas, that can diffuse back up through the substrate into oxygen rich water where it can bond with oxygen (or whatever it will) and be rendered safe for aquarium inhabitants and plants can gobble it up.

there's others (most) that will go through all this, not all have toxic forms.
and there's side-effects (if you want to call it that)

you are required to stop disturbing your substrate, no replanting, no rescaping, all that moving around allows oxygen to move into deeper sections of the substrate ensuring that no anoxic zones will develop.

even the toxic H2S, that sits there comfortably in those lower levels, ... it's not disturbed, it stays there, diffusing up slowly enough that your fish remain safe, if you're going to move stuff around, you're asking for trouble.

so don't, under any circumstances, set up a DSB, let it's do it's thing for a while, then decide you don't like your plant arrangement, ... as doing this, you are the reason your tank is having such a hard time. don't blame the science, blame yourself.

 

[Caliban07]

liquid aquarium fertilizers add nutrients to the water column

not the substrate

fish poop, and that will filter down into the substrate, that will break down due to bacterial activity, ... as the detritus breaks down nutrients are available for plants to take in through their roots

fertilizing the water column, plants will absorb through their leaves.

nutrients in the substrate to be broken down into forms available for plants, ... requires deeper substrates.

and this gets people scared

some nutrients can be processed from detritus into nutrients the plants can used with aerobic areas in the substrate (everything in the substrate that has access to abundant oxygen)

some nutrients can only go so far and bacteria will only process it so far because energy from processing those nutrients isn't efficient and the bacteria will process other nutrients

... so there's a bunch of nutrients that will accumulate in the substrate that cannot be processed unless the environment in the substrate changes to a point that processing these nutrients become a do-or-die situation for the bacteria.

these sections nutrient turn-around is very slow, there's not a lot of energy gained in processessing these nutrients, the bacteria here for all intents and purposes are slower.

and this happens in the lower areas of the substrate where free oxygen is either limited or completely lacking.

and people worry about H2S, ... which in moderation is where you're getting your sulfur for your plants. (this is one of those i'm familiar with that requires this anoxic zone to be processed), ... yes it's a very toxic combustable gas, that can diffuse back up through the substrate into oxygen rich water where it can bond with oxygen (or whatever it will) and be rendered safe for aquarium inhabitants and plants can gobble it up.

there's others (most) that will go through all this, not all have toxic forms.
and there's side-effects (if you want to call it that)

you are required to stop disturbing your substrate, no replanting, no rescaping, all that moving around allows oxygen to move into deeper sections of the substrate ensuring that no anoxic zones will develop.

even the toxic H2S, that sits there comfortably in those lower levels, ... it's not disturbed, it stays there, diffusing up slowly enough that your fish remain safe, if you're going to move stuff around, you're asking for trouble.

so don't, under any circumstances, set up a DSB, let it's do it's thing for a while, then decide you don't like your plant arrangement, ... as doing this, you are the reason your tank is having such a hard time. don't blame the science, blame yourself.

Hi flear

My question really is not about a self sustaining aquarium. Don't most aquarium plants take nutrients in through their leaves rather than the substrate?

 

[Flear]

both
even floating plants have roots for a reason

all plants can absorb nutrients through their leaves

in an aquarium, ... adding all those nutrients to the water column, ...

well the nutrients can sit in one place or another or a mix of both.

but in the water column you'll never get as many as you can get in the substrate.

somewhere i have heard roots absorb about 80% of their nutrients through their roots, ... granted i'm not going to trust that memory as i think it was relating to the way roots absorb nutrients for terrestrial plants

but even terrestrial plants you can spray the leaves and feed them that way, ... the leaves can absorb nutrients, but it's not their design.

the roots are for more then just anchorage.

 

[Caliban07]

both
even floating plants have roots for a reason

all plants can absorb nutrients through their leaves

in an aquarium, ... adding all those nutrients to the water column, ...

well the nutrients can sit in one place or another or a mix of both.

but in the water column you'll never get as many as you can get in the substrate.

somewhere i have heard roots absorb about 80% of their nutrients through their roots, ... granted i'm not going to trust that memory as i think it was relating to the way roots absorb nutrients for terrestrial plants

but even terrestrial plants you can spray the leaves and feed them that way, ... the leaves can absorb nutrients, but it's not their design.

the roots are for more then just anchorage.

Yes that is undisputed. However, should it be enough to feed through the leaves?

 

[Flear]

it should, this is regular fertilizer regime practiced by most people in the hobby.

those "most people" who have a substrate of sand or gravel with no nutrients for the plants to obtain here as this was never considered, ... then they get plants and hope to keep them alive

the alternative (if following Walstad) organic potting soil, or there is Mineralized top soil (MTS) and a few others out there that start with a system to ensure nutrients are available for the plants from the start.

otherwise you are a slave to dosing liquid fertilizers, unless you get creative and mix your own from chemical nutrient sources - there are several receipes for making your own fertilizers as well online ... either way, you are a slave to feeding your plants, ... and to ensure nutrient levels don't reach toxic levels (while still providing minimums) you are required to maintain regular water changes

the plants absorb these from the water column

over time fish poop may accumulate and break down in the substrate, and allow their roots to actually be roots (taking in nutrients), but before this happens the plant roots aren't doing much other than holding the plants in place.

 

[GodFan]

Its a cycle. The fish eat and poop. The poop makes nutrients and the plants absorb them. Keeping the water clean. If you are just trying to keep the water clean that is the simplified process. Low maintainance plants and low bioload are a must. As is a good substrate.
If you are trying to make it selfsustaining to tbe point you dont even feed then things get more complicated. You will need a large tank or miniscule fish. The best example I can offer would be scarlet badis and red cherries. The badis will (in theory) get all their food from shrimplets and whatever other micro creatures they find. The shrimp should eat off dead plant matter.
In a large tank you can add extra steps and such. In a large enough tank you could have a breeding population of livebearers to feed a larger predatory fish. You can take the food chain all the way down to inverts. For example pond snails and mts are great food for assassin snails. As an extra bonus a dwarf cray will eat the leftovers of the mts.

Basically you can make this as simple or complicated as you want. My dream tank is a complete ecosystem. It would have an open area up top with emmersed plants housing frogs. Below that would be the water with a balanced ecosystem of fish and inverts.

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[Flear]

GodFan, i haven't looked into the scarlet Badis specifically, but hessitate one one principle alone

diet, ...

when i was initially looking for the apex preditor (if that's the correct way to refer to it), the big guy at the top of the food chain ...

i searched, and ask for assistance in my search for omnivores with a preference towards plants.

before i was suggested the florida flagfish results were dissapointing.

-herbivores typically start at 6"+
-omnivmores typically start at 4"+

unless i'm looking into huge tanks for an experiment those are insanely huge fish for a hobbiest for such an experiment

the florida flagfish at just over 2" was perfect for me

well if i had the choice of smaller i would, but i haven't seen anything under 4" that cared about plants of any sort (including algae)

plants grow, they consume nutrients, but plants are needed for self-sustaining so the fish don't kill themselves with nitrates in the water

i wanted a system where the plants would be kept under control by the fish, but still have plants

the flagfish is very small, and despite it's dietery preferences i've found a problem, ... the reason most herbivores start so large is their mouth is big enough to do damage to plants, ... so the flagfish posed an aditional problem, finding plants with leaves small enough/fine enough the flagfish can nibble on, ... searches for that ... well i've got a physical description as asking around hasn't given me much for answers

the scarlet badis you suggested, ... would let algae and plants run out of control till leaves accumulated that would be blocked out from light or run into deficiency problems that would impair the health of the plants and i worry about that unsettling the balanace in a self-sustaining aquarium.

one day i may consider larger fish (other omnivores) or even herbivores (which would allow me to use bladderworts that would allow zooplankton that could eat phytoplankton, that would assist with ensuring nutrient levels in the water column don't get excessive. ... but that's a possibility i'll consider another day.

for now i'm using flagfish for what it helps and the problems it adds

meaning i am also doing what i can to ensure plenty of algae growth, ... which if the nutrient levels being released by the substrate are sufficient to allow for high density greenwater that i require help at keeping phytoplankton levels down, ...then there will be suffient nutrients to allow algae in the tank that i know the flagfish will eat

... it's all based on ensuring the diet of the apex predator (if that's the right term in this situation)

others i've seen consider & talk about their experiments with self-sustaining tanks, ... treat it like guppy/endler fry don't need food (but they need some form of bacteria or phytoplankton (or even bacterioplankton) in the water they can eat till they are large enough to eat zooplankton, ... to be sustainable food for the betta (as one example i have heard)

also heard of a lady who heard betta fish are a great way to keep guppy populations in control, ... she finished off her story with the guppy population ran out of control, and she had a fat lazy betta, ... didn't work

 

[aqua_chem]

Its a cycle. The fish eat and poop. The poop makes nutrients and the plants absorb them. Keeping the water clean. If you are just trying to keep the water clean that is the simplified process. Low maintainance plants and low bioload are a must. As is a good substrate.
If you are trying to make it selfsustaining to tbe point you dont even feed then things get more complicated. You will need a large tank or miniscule fish. The best example I can offer would be scarlet badis and red cherries. The badis will (in theory) get all their food from shrimplets and whatever other micro creatures they find. The shrimp should eat off dead plant matter.
In a large tank you can add extra steps and such. In a large enough tank you could have a breeding population of livebearers to feed a larger predatory fish. You can take the food chain all the way down to inverts. For example pond snails and mts are great food for assassin snails. As an extra bonus a dwarf cray will eat the leftovers of the mts.

That's the thing though, it's not really a cycle. It's more of a linear/pyramid model, depending on how you look at it.

Really, you have two things that must be considered: energy and nutrients.

For energy, the reality is that you cannot supply enough energy without external inputs to meet the demands of an obligate predator. The ten percent law, which states that only 10% of a lower rung's energy in the food pyramid gets. But the most important thing that he does is periodically add leaves to the tank. This dramatically increases the energy/nutrients of his tank by simulating plant breakdown (in 'the wild', a tree on the edge of a lake would have been absorbing nutrients and energy all year). This makes the 'size' of his tank effectively his aquarium plus a tree to harvest light and supply energy to the rest of the tank.


What I'm trying to say is that an aquarium simulating an ecosystem is a definite possibility, if somewhat difficult to execute. A natural aquarium with a 'self contained' ecosystem is about as unnatural as you can get.

 

[aqua_chem]

My question really is not about a self sustaining aquarium. Don't most aquarium plants take nutrients in through their leaves rather than the substrate?

Different plants prefer different routes. It's all on a spectrum. Some, like crypts or swords, will prefer root routes but will still absorb a minority via the water column. It's the opposite for stem plants, generally speaking. Also it's not like there is a definite barrier between water column and substrate. Many ferts will move between the two based on relative levels.

 

[aqua_chem]

Yes my experience has been the same. Plants perk up with top offs or water changes.

Interesting fact, that's actually magnesium you're seeing. It can be rapidly integrated into plant structure such that you can see changes in the same day. It's fairly unique like that, as many other nutrients cannot be redistributed like this (see: immobile nutrients).

 

[Caliban07]

Interesting fact, that's actually magnesium you're seeing. It can be rapidly integrated into plant structure such that you can see changes in the same day. It's fairly unique like that, as many other nutrients cannot be redistributed like this (see: immobile nutrients).

How do I ensure my plants get these nutrients. I chose only stem plants for this reason.