# self-sustaining aquarium



## Flear

if there is a more appropriate place for this thread, please advise and move 
---

how many people here are interested in the idea of a self-sustaining aquarium ?

those that have thought about it, but not tried. ?
those that have tried, maybe it failed, (what was learned) ?
those that have curiosities that may need to be considered at addressing such an idea. ?

-first, looking for other minds with similar interests, or those who have learned a thing or two from the attempt


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## rpadgett37

Flear said:


> if there is a more appropriate place for this thread, please advise and move
> ---
> 
> how many people here are interested in the idea of a self-sustaining aquarium ?
> 
> those that have thought about it, but not tried. ?
> those that have tried, maybe it failed, (what was learned) ?
> those that have curiosities that may need to be considered at addressing such an idea. ?
> 
> -first, looking for other minds with similar interests, or those who have learned a thing or two from the attempt


I have an interest in this area myself. I can't say that I understand how plants fit into the nitrogen cycle very well, but I will have a tank set up in the next couple of weeks that will use plants exclusively as the filtration system.

It is a small BW aquarium with a very low PH that I am stocking with tiny nano fish. As I understand how these work, you can't grow out nitrifying bacteria because of the low PH, so you have to use plants.

I'll be using Hornwort, planted wisteria, frogbit and duck weed as the plants. All fast growing, with the nutrient hog Hornwort as the center piece. This will be my first attempt at something like this.


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## Flear

will read more later when i have more time

plants can either take in ammonium directly (if your pH is low) or they will take in nitrates (costs the plants more energy to process as they run nitrates backwards through the cycle till they have ammonium 

ammonia is not the same as ammonium here

as the plants will suck back nitrates, this is removed from the equation of any reason for water changes, nitrates will not build up, ... unless you are overstocked and/or don't have enough plants to handle the amount of nitrates being produced in your tank


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## Flear

low pH screws up the nitrogen cycle

all potential ammonia is converted to ammonium
ammonium in non-toxic to fish, ... not low, but non-toxic, ... you could have lots of ammonium and still be fine

a low pH being under 6.5.

plants can absorb directly ammonium and use it, and are very happy to do so 

test kits don't test ammonium, only ammonia, so how much you have in your tank becomes a mystery, ... and the plants are just happy it's there.

---

word of warning, ... if your pH shifts though, ... say it reaches 6.8, ... all your fish die due to ammonia spike.


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## Mikaila31

Most test kits do actually test for ammonia/ammonium. The most common one in this hobby - API 'ammonia' test does test for both. This is considered a total ammonia test (NH3/NH4+). You can get tests that just test for free ammonia which is just NH3.

Self sustaining is not possible since a natural ecosystem itsn't self actually self sustaining either. There are a massive number or reason it would not work long term. Also attempting it would severely limit what you can do and keep.


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## Flear

it tests for ammonia, requires you to know your pH, then you look through the chart to see remaining ammonium

wait, that's nutrafin, ... well that's how that one works


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## rpadgett37

I must apologize as I jumped into this thread a little too quickly.

My knowledge at this point is pretty much limited to the front end of setting up and cycling the aquarium. What is lacking for me is knowledge of how to sustain the aquarium. By that I don't mean the usual maintenance and water change tasks. I mean the care and maintenance of the eco-system... plants, nutrients, and so forth. I understand very little of what give and take is happening among the plants, bacteria and fish that inhabit the aquarium, and what role I play in encouraging and maintaining that balance. Also in terms of what tools do I use while fulfilling the role of care taker.

My tank I described above is the first where I will have to use plants alone for the filtration. I am very interested in how to help that along so it works well. That is far from creating a self-sustaining environment, which I am quite certain is beyond my grasp right now.

I am going to follow this thread, though, as I am certain to learn a thing or two as it unfolds.


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## Mikaila31

Flear said:


> it tests for ammonia, requires you to know your pH, then you look through the chart to see remaining ammonium
> 
> wait, that's nutrafin, ... well that's how that one works


APIs test is for total ammonia - both NH3 and NH4 are reported on that test. It does not differentiate between them. Total ammonia is the idea ammonia test to use since NH3 and NH4 don't really matter apart from they should not be in a stable tank. If you add prime or something its going to lock all ammonia as ammonium for 1-2 days so again regardless. You want to know total ammonia since even the mostly non-toxic ammonium should not be present in a stable aquarium. Ammonium is a precursor to nitrite same as ammonia, if the biofilter gets ammonium it will still produce nitrite. Thus we care most about total ammonia not free ammonia.


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## corina savin

If there is no bacteria, then there is no nitrate.
A pH 6.5 is not low enough to slow down the bacteria.
Even if your test show zero ammonia/ammonium, zero nitrite and zero nitrate, you'll still have to do water changes. Plants will need minerals (over time, they will deplete). Also, fish release pheromones into the water. Pheromones accumulate over time, signaling "crowding". Fish stop growing.
Water evaporates, needs replaced, unless it rains. pH keeps dropping because of organic acids. Some fish can go as low as 3.
Too many things to think about...


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## Flear

plants can be used alone to ensure nitrates are at acceptable levels, ... if you have lots of plants and/or low bioload.

some fish this alone will provide all that's necessary that you don't have to change the water.
other fish this is a recipe for heartbreak to come home to dead fish.

different fertilizer styles change things.
some fertilizers are based on ensuring nothing gets to low,
some fertilizers are based on the idea of providing lots, ... possibly more than your plants could use, and so you must preform water changes to prevent things from building up to toxic levels

after this, i don't have clear reasons for or against regular maintenance as any reason could be contradicted by the next.

if i do regular maintenance on my one tank i won't learn what could go wrong, it won't inspire me to seek answers because i will never know what is going wrong to know what to search for

this also has drawn some criticism,


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## Flear

corina, organic acids may drop pH
dissolved minerals raise pH also


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## Mikaila31

Flear said:


> some fish this alone will provide all that's necessary that you don't have to change the water.


Not sure why you still believe this. But no. Some fish may _Survive _longer then others but thats not meaning necessary or non-necessary.


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## Flear

mikaila, good clarification.


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## Flear

*Substrate*

is it possible to solve issues between anoxic zones in the substrate and roots adding O2 to the substrate ?

a DSB allows for Anoxic substrate.
needed for processing nutrient cycles
-i don't have a full list of each nutrient, but enough to know without any anoxic area, various nutrients will build up in forms nothing can use.

roots add oxygen into the substrate (for the health of the root)

are plant roots an enemy in this ?, or is there anything that can be done that would ensure that over time there will be anoxic areas that will remain to finish cycling these nutrients ?


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## jaysee

Flear said:


> if i do regular maintenance on my one tank i won't learn what could go wrong, it won't inspire me to seek answers because i will never know what is going wrong to know what to search for


As the saying goes - when everything you've done is wrong, what's left is what's right. Certainly there is more to learn from failures than there is from success. Anyone can simply follow instructions and succeed - doesn't mean that they understand why it is they do the things they do, or more so, the "risks" associated with deviation from the instructions. I mean, I can follow instructions and bake a cake time and time again. And then a cake comes out messed up - not that I have any idea why, cause all I've ever done is follow instructions to success. Now had I not enjoyed immediate success through directions, I would have more failures under my belt - enough to be able to deduce that I used too much flour or whatever.

Too, anyone who is not willing to risk "failure" is not going to learn much about capacities and limitations.


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## Flear

jaysee, ... thank you 

now if i more of a mind for scientific process ... 

process is so painfully slow at times 
at times i just go with what i feel, which gives more inspiration into ideas that i think i would ever have otherwise


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## Mikaila31

You would need to make the substrate deep enough that plants would not root all the way down, or have significantly large unplanted areas to try and encourage anoxic zones but that wouldn't be a guaranty especially with heavily rooting plants. Also minimal to no current. Then you have to realize these conditions will have on more then just anoxic zones. 

You are still lingering on nutrient cycling and redox which is again just the beginning of how an ecosystem operates. You fix the anoxic issue then there will be another issue and so fourth and so on. Issues that will have nothing to do with nutrient cycling and all about biological stability and viability. 

Mulm build up and nutrients falling out of cycle is natural. Cycles are not indefinite, nutrients are always being added or removed to the system both organically and inorganically. You can keep asking and looking for ways around this but it is what it is. There is no current magic that lets you break physics yet and give you something for nothing. 

I am all about pushing limitations and currently do and have for many years. The more natural you want to go the more the tank is going to look like it belongs in a swamp. Then when you get to the point where you don't even want to stick your siphon in there let alone your hand, you will then question why you bother pushing such limitations. Sure fish seem happy, plants look like crap from build up of mulm, any optional powerhead is probably clogged by mulm now too regardless of it if has any 'filtering' abilities. By then you have seen so many population explosions of things you have no clue of so you just let them be and wait for them to crash before touching the tank any further. I have lots of pictures of lots of things you generally don't want your tank to look much like both from the past and the present.

So yeah just change water, its much easier and rewarding IMO. You can do anything along with, soil substrates, non-filtered, ect and still be good.


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## Flear

Mikaila

you have no idea how thankful i am of your advice
i'm thankful i'm stubborn, or i would have given up

the redox and nutrient thing may be the basics, ... have to start somewhere (i'm guessing 5"), ... yes, it's got issues that i can't imagine how to overcome, aside from floating plants, not quite what i would prefer, ... and floating plants are only floating till their roots find ground, then they become anchored 

ya, that's an area i don't have a fix or idea for.


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## jaysee

Honestly, I think it would be an eyesore to have 5 inches of substrate in the tank.


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## Mikaila31

some plants are strict floating plants, other are considered rootless. Duckweed, dwarf water lettuce, hornwort, then the mosses are not considered rooting plants, roots primarily provide attachment are and very short.Anchored is diff then rooted. Most all stem plants have minimal roots that primarily anchor. 

On the other hand an amazon swords roots can easily cover a 2x2' area. 

Far as pore size I would say smaller, many plants root better in fine gravel then sand... but not always. Fine gravel to straight up topsoil my tanks still get good root development against the bottom glass with 3" of substrate.


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## Flear

mikaila,

i've got ideas on ensuring the life is going round and round, ... doesn't mean it will run stable, only that i've got ideas, including ideas that could naturally keep things in check (well 2 ideas for one situation)

i think over time as i look at things i may find a half-way point between this pursuit of self-sustaining and mechanical intervention, ... for now, while i'm running things around in my head, ... if i can do it in the aquarium, naturally, without need for me to get/use/install equipment, great this is what i will do.

if i can get it far enough that the only inputs i'm giving is energy sources, by all means i'm all for that long before i even begin, and this would be the optimal goal.

if i give up because of looks, then i'm a hypocrite


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## Flear

Mikaila, ... 

you mentioned you think the tank (if i solve the nutrient cycle thing) would take on more of a swamp-like appearance.

this is going to sound so totally braindead on my part, ... what would that look like ?

in my imgaination i think of an overgrown area with plants and trees growing out of the water, heavily planted, duckweed, greenwater, ... but can't really picture more than that.

would that be about right, or is there other stuff you are thinking would happen ?


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## Roccus

Flear said:


> Mikaila, ...
> 
> you mentioned you think the tank (if i solve the nutrient cycle thing) would take on more of a swamp-like appearance.
> 
> this is going to sound so totally braindead on my part, ... what would that look like ?
> 
> in my imgaination i think of an overgrown area with plants and trees growing out of the water, heavily planted, duckweed, greenwater, ... but can't really picture more than that.
> 
> would that be about right, or is there other stuff you are thinking would happen ?


I' have a neighbor that asked for my assistance with their fish tank while they were admiring my ornamental pond.... their 10 gallon planted "guppy tank" was( is) the classic swamp.... I needed a mag light to look through the algae covered glass... dead and dyeing plants abound.. some sticking out of the tank.. I've seen septic systems that were cleaner... the woman told me the water hadn''t been changed in over a year.. they add water when the water level gets below the rim... did I mention the white crud covering the frame of the tank and light fixture...the guppies were alive .. so I guess that it is a self sustaining tank....I told her unless she was willing to follow a schedule i set up that I wanted no part in the "rescue".. she seemed to think that weekly water changes are unnessesary and troublesome... in the end she said she was just going to scrape the glass.. I wished her well and went home.... and stared at my tank(s) for an hour... enjoying the crystal clear water and active multispecies fish... IMHO, a bucket or two of water once a week is a small sacrfice for the enjoyment i recieve at watching my tanks...water chemistry is a complex thing... and for it to be the optimal home for our pets IMHO, we need to do the best for them we can.... and that includes removing nitrates, and replacing lost buffers and mminerals by doing regular water changes...


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## Flear

so ...
-things in the tank to deal with greenwater being too thick
-ensuring enough potassium for greenspot algae (and ensuring sufficienty other nutrients present to ensure there are no nutrient deficiencies
-plants that are edible and preferable to fish & critters pleasant.
-snails to deal with detritus in all it's forms

anything i missed or would that have solved every issue you saw ?

Edit:
i would never do this with a 10gallon tank, way too small

preferences, even for first attempt i would not recommend smaller than a 40 gallon

for arbitrary tank sizes, ... i've thought (as for round tanks) 1' diameter for each inch the species is long (this is worse than the gallon per inch rule of thumb, but gotta start somewhere)


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## Mikaila31

there must be some limit to all growth to maintain stability. not sure when you intend to have all nutrients, well apart from carbon non-limiting constantly. 

plants and algae occupy the same niche and directly compete. They both cannot be happy, you will lose plants typically in this situation. Or with happy plants they can produce compounds that work to inhibit algae. Typically greenwater should not be dense enough to be noticable, naturally this favors low O2 levels in the water column. 

you have no understanding of mulm, detritus build up. Same with biofilms. I can post some horror pics of my tanks later.
_Posted via Mobile Device_


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## LittleBlueFishlets

Flear, 

OldFishLady had the closest example to self-sustaining tanks that I know of. (I'm not saying that other people don't. It's just that I read her posts about her tanks.) She isn't active on BF/TFK anymore, but you may want to read her threads about it. 

Her tanks were heavily planted, and did not require frequent water changes. (But she did do occasional ones. In some of her posts, she discusses the frequency/infrequency of them.) The threads/posts I've seen were all on Bettafish.com, so you may want to look there. Also, it's worth looking at the photos in her albums (if they're still there). That may help you see what plants she had success with. Even though she's not active on the forum anymore, you may want to try PMing her to discuss this, if there's something you want to know more about. (Assuming she still has the option turned on to receive emails when a PM is sent.) 

As for the ammonium/ammonia discussion, I just posted the following on Bettafish.com:


LittleBlueFishlets said:


> Ammonia test kits often don't distinguish between NH3 and NH4+. They just give you a "total" reading. Therefore, if your API test kit turns light green, it only tells you that the combined NH3/NH4+ reading is approximately 0.25ppm. But it doesn't tell you how much of each is present.....
> 
> We know that at a higher pH, there is more NH3 present (bad), and at lower pH, there is a shift towards a higher amount of NH4+ (less toxic). So below is an estimate of the relative percentages of NH3 at different pH values.
> 
> *At a water temp of 25C (77F):
> pH 6.0: Approximately 0.056% of Total Ammonia is in the form of NH3.
> pH 7.0: Approximately 0.56% of Total Ammonia is in the form of NH3.
> pH 8.0: Approximately 5.6% of Total Ammonia is in the form of NH3.*
> 
> To determine how much NH3 is present, multiply the above % by the reading on your test kit. For example: Your test kit turns light green (0.25 ppm).
> If your pH is 7.0: 0.25ppm x (0.56/100) = 0.0014ppm NH3.
> At pH 6.0: 0.25ppm x (0.056/100) = 0.00014ppm NH3.
> 
> Assuming that the nitrifying bacteria require NH3 to grow, then it makes sense to me that the lower levels of NH3 (which occurs at the lower pH) will slow down their growth (and stall your cycle). They simply aren't getting enough "food."
> 
> (Please note: These numbers are estimates, and assumes that ONLY pH is the only factor in the equilibrium shift between NH3 and NH4+..... But this will at least give you an idea of the relative concentrations in your tank.)
> 
> *Note: The above was for those who scored a low value in Jaysee's poll.  For those of you who selected a 10, read on. (Insert evil laughter here.)*
> 
> I used the Henderson-Hasselbalch equation to determine the relative ratio of NH3 to NH4+ at different pH values: pH = pKa + log ([NH3]/[NH4+])
> 
> In the above equation, Ka is called the acid dissociation constant. All acidic substance, including NH4+, have these values. It's a measure of the extent to which the acidic NH4+ dissociates in water to become the basic NH3. The values are easiest to find for "room temp" which is considered to be 25C (77F). At this temperature, the pKa for NH4+ is 9.25.
> 
> Now on to the math: (Are you still rating yourself a 10 on Jaysee's poll?)
> 
> If your pH is 6.0:
> pH = pKa + log ([NH3]/[NH4+])
> 6.00 = 9.25 + log ([NH3]/[NH4+])
> The ratio of [NH3] to [NH4+] = 0.00056
> Multiply by 100 to turn this into a percent.....
> So 0.056% of the Total Ammonia reading on your test kit is due to the presence of NH3.
> 
> If your pH is 7.0:
> pH = pKa + log ([NH3]/[NH4+])
> 7.00 = 9.25 + log ([NH3]/[NH4+])
> The ratio of [NH3] to [NH4+] = 0.0056
> So 0.56% of the Total Ammonia reading on your test kit is due to the presence of NH3.
> 
> If your pH is 8.0:
> pH = pKa + log ([NH3]/[NH4+])
> 8.00 = 9.25 + log ([NH3]/[NH4+])
> The ratio of [NH3] to [NH4+] = 0.0056
> So 5.6% of the Total Ammonia reading on your test kit is due to the presence of NH3.
> 
> The above is in line with the pH scale, which is a logarithmic scale. Each increase/decrease of one unit is a ten-fold increase/decrease in the concentration of H+ ions. (H+ ions are what makes a substance acidic. More H+ ions = more acidity = lower pH.)


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## Flear

i haven't posed questions or looking for answers for mulm/detritus, ... doesn't mean i don't know anything, doesn't mean i do know enough, ... only means it hasn't been anything i've spoken of.


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## Mikaila31

Well would be interesting to hear your opinions on those. I personally run as natural tanks as I can BUT I normally push those tank for high productivity. You want a biologically self sustaining aquarium, I personally go for the monetary self sustaining aquarium. Means low budget, DIY, and low upkeep too. Production is high and thus tank covers its own costs with output. But regardless i have set up tanks to push boundaries just to see what would happen. I can say the first year of 'neglecting'(or testing the sustainability) a tank is the easiest. It will be the microfauna and microflora that will cause issue. Some are transient boom and bust cycles which are typically in a unbalanced system. You can certainly achieve balance, maintaining it tho is a whole another thing. 

Most my productivity tanks are soil tanks. I use topsoil mainly almost always with some additives then usually a sand cap on top of 1-3". I do have a bare soil tank running currently tho that has a substrate of just 2.5" of mineral enriched topsoil. I'm quite picky about my topsoil too. I've used both store bought and hand shoveled topsoil, the first is always more questionable IMO. Below are some of my sustainability tanks not driven for high production and more for simply seeing what happens.










Biofilms are yummy and they happen typically when you have unfiltered tank that is unmaintained biofilms come and go due to specific nutrient availability and such. Typically start as the 'oil film' on the surface if you have little to no surface movement they can get impressive. Surface movement mechanically breaks them down but most microorganisms don't like much movement, let alone filtration. Typically a biofilm like that lasts awhile, normally fish are fine, and normally I don't touch my 'whatever' tanks when they do this. They can stick around for a long time eventually zooplankton catch up and there is a swift boom and bust cycle, population explosions and collapses happen very fast when you simply let it run its coarse. That biofilm pictured above was around for a couple months then collapsed in about 48 hours do to a zooplankton boom. Then the zooplankton collapsed shortly afterwards. I've had this happen in multiple tanks multiple times. 

Detritus and mulm become an issue eventually. Either stagnant or circulating tanks I have had this be an issue. Snails and shirmp make it worse IMO by adding to it. Without them you still have natural biological fallout from nutrient cycling. Bacteria, phytoplankton and zooplankton all naturally die in relatively short lifespans. This is the main source of mulm IMO in this kinda setup. 









This is a previous filterless soil-based tank that did have circulation. After over two years some biological change caused excessive mulm build up and eventually I tore it down and redid the tank/substrate. 








This is a current running tank. It is my bare- soil tank and it is stagnant. Mulm build up and such no shrimp and very few snails. Currently the rate up build up is slow enough no to be a concern.








Difficult pic to decipher. This is the same tank as the previous pic. What this is, is a localized nutrient deficiency. Again stagnant water and relying on diffusion is limiting even with 2.5" of topsoil its not a fool proof way to ensure nutrients. And localized deficiencies are naturally common. In this tank a large mass of bladderwort grows directly under the lights and has been having a major party with some cyanobacteria lately. Both are very good and happy with nitrogen deficient conditions. Being on the surface directly under the lights means they have the highest energy input zone which drives nutrient uptake and suddenly your lacking nutrients there. The duckweed in this tank also barely manages. Meanwhile the anubias and ferns beneath have no such issues with nitrogen. 

I've never really had any of my long term 'neglected' tanks maintain macro/vertebrate life long term. Especially adult fish or fry. But again limits, typically the water column is nutrient devoid. If nutrients are available something will try to use them. Then competition, and whatever is most efficient usually pushes out its competitors either temporarily or long term. The chemical/nutrient cycles are a step in understanding the biological cycles. The biocycles effectively drive the nutrient cycles.

In comparison to my maintained tanks which are initially not that different then my unmaintained tanks I find my unmaintained tanks meh, which in a way perpetuates their being unmaintained. Some are both soil tanks with same basic setup and in the end differences that leads to super happy and crazy plants and excessively stocked happy fish is simply maintaining them and changing water. And by maintained I mean I had to spend 3 whole minutes of my life laying on my couch tonight watching one of my high productive tanks finish filling to the trim for is 50% weeklyish change. But I do understand we all find different things rewarding.


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## keepsmiling

Snails add more bioload and crap than people realize. This sounds like an experiment that may cost the lives of some fish. 
What is the issue with just changing water?


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## jaysee

Roccus said:


> I' have a neighbor that asked for my assistance with their fish tank while they were admiring my ornamental pond.... their 10 gallon planted "guppy tank" was( is) the classic swamp.... I needed a mag light to look through the algae covered glass... dead and dyeing plants abound.. some sticking out of the tank.. I've seen septic systems that were cleaner... the woman told me the water hadn''t been changed in over a year.. they add water when the water level gets below the rim... did I mention the white crud covering the frame of the tank and light fixture...the guppies were alive .. so I guess that it is a self sustaining tank....I told her unless she was willing to follow a schedule i set up that I wanted no part in the "rescue".. she seemed to think that weekly water changes are unnessesary and troublesome... in the end she said she was just going to scrape the glass.. I wished her well and went home.... and stared at my tank(s) for an hour... enjoying the crystal clear water and active multispecies fish....



Hahahaha, sounds just like someone else's tank many of us know about....only instead of 1 year without a water change it's several.


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## Roccus

jaysee said:


> Hahahaha, sounds just like someone else's tank many of us know about....only instead of 1 year without a water change it's several.


;-)...I've been around this site long enough to know who you mean....


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## jaysee

Guppies and all


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## Agent13

Roccus said:


> ;-)...I've been around this site long enough to know who you mean....



Haha.. Any of us tooling around here for a while must wonder "is that his wife ?" 


Sent from Petguide.com App


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## Roccus

Agent13 said:


> Haha.. Any of us tooling around here for a while must wonder "is that his wife ?"
> 
> 
> Sent from Petguide.com App


 
:gossip:... we all should be so.. but it's Friday and it's all in good fun...:twisted:


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## Flear

keepsmiling, the more i know ahead of time, the more i know when it's not working and i have to intervene

mikaila, you're right, we all find different things rewarding, thanks for the pics and info, tons to think about


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## keepsmiling

Flear said:


> keepsmiling, the more i know ahead of time, the more i know when it's not working and i have to intervene


It's really quite simple, but you can make it difficult if you so choose. ;-)
An aquarium is a closed system. YOU are the caretaker. Take care of it properly and it will reward you with it's health and beauty. Neglect it, or deny it's basic needs and it will disappoint and frustrate you with algae and death.


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## Flear

keepsmiling, if only that was the only reason people did things i would agree, ... of course then we'd still be living in caves delighting at the gift of fire from the gods.

even Mikaila, who has shown some less than desirable tanks for many to own, has demonstrated the desire to push limits and learn, ... not all of us find the same purpose in having an aquarium, some of us like to learn as well


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## Mikaila31

Its not the bioload of snails/shrimp its the dynamics of they system. An aquarium is small in comparison and a single species can have an significant impact on a whole lake or pond, the smaller aquarium will usually show a greater effect faster. 

The snail/shrimp will have an impact on biofilms since they feed off them, they will push for them to become more snail/shrimp resistant when they otherwise would not be. I know it all seems small but this is what makes up an ecosystem. It is an complete dynamic web of all organisms. The more diverse an ecosystem is the better, that is what makes invasives so damaging to existing ecosystems. Its the direct and indirect effects they bring. Not all are predictable. If you want some real life comparisons then look at the rusty crayfish and earthworms in the midwest region, both are invasives. We have no native earthworms up here, but we do have over a dozen invasive ones these days. Both have a noticeable impact on their ecosystem, specifically a great effect on lowering plant diversity which ripples out to everything directly or indirectly dependent on those plant species. 

Biofilms/awfuchs are very important and complex. Many rivers and lakes for example don't have sufficient plants to maintain the ecosystem, instead the primary producer in the system is the biofilms and awfuchs. The rift lakes are an example, cichlids don't mix with plants because they are not natural to them. They eat awfuchs and invertebrates off the rocks. Many northern rivers are similar either algae is the main producer or it falls to external input. Trees, logs, leaves... fall into the rivers and lakes an a wide range of invertebrates feed on these and eachother then fish feed on the inverts. That external input voids the need for aquatic plants in many systems.

Pushing limits is always good IMO. But you need to have control too. First thing with self-sustaining is your giving up control. The system is too complex, dynamic and too small to maintain a single perpetual state on its own. It simply hasn't been done, even on a large scale like the biosphere/biosphere 2 project. At the very least there was more space and more control for that experiment and they had multiple biomes. An aquarium is almost fully closed, even unmaintained you have movement of gases and water with the atmosphere. The tank will be taking up CO2 constantly so its not completely closed. Along with no aquatic ecosystem being anywhere as closed as an aquarium, self-sustaining just isn't viable. Even cutting a entire/lake or pond out of nature and encasing it in a glass bubble it will not self-sustain itself. 

Those tanks above would be fine with maintenance and occasional pushes towards where you want them to be going. They are/were not setup any differently then most my other tanks, which are still low maintenance IMO. Bare soil and unfiltered is certainly possible and not that hard to do but I personally wouldn't suggest uncirculated in most situations.


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## Flear

even for me to consider a self-sustaining aquarium, ... i recognize that there is no part in it that allows for how things are in the wild.

a single fish in the wild will cover more area in a single day than the size of most of our tanks (exceptions being the largest tanks of what's out there)

much of what i am thinking involves ensuring each part of the food chain can sustain it's numbers with growth and reproduction of whatever is eating it. ... a vicious chain.

as Mikaila suggests over and over, ... it's not very likely i'll ever achieve that, ... i will have fun trying though  if i can, great, if not i'll have learned a ton along the way


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## Agent13

And I'll have learned while watching your shenanigans flear >.<

I do enjoy watching your threads even if I don't always comment . Tis a great arena to learn odd bits and pieces .


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## Flear

on a small scale, ... for a year, i had mainained a 1 gallon betta bowl (no fish) that i would call self-sustaining.

had snails, had microworms, had what i am guessing small planaria.

at one point i added algae, (duckweed made it's way with the algae). it sat by the window, the algae exploded in there till it filled it, i removed that, fed the flagfish in the tank, ... yes, that's removing nutrients, ... i have been largely experimenting with that bowl

i added greenwater, added a pinch of algae since, ... the greenwater is pale green/yellow, the algae is slightly larger, i haven't seen any microworms in there in a long time (or planaria) i do notice at least 2 different kinds of zooplankton skittering around the glass inside (really small i don't know what kind at all)

most of the changes i have induced in the bowl, ... some changes i made, made permanent other changes (no worms anymore).

the snails are doing well in that bowl, the Malaysian trumpet snails have a long sharp shell suggesting ph is high.

---

above all, it shows me things are possible. a small bowl maintaining critters (also small) shows a self-sustaining idea is possible, ... the critters available, ... i don't have a clue how large a comparable tank would have to be to house fish, ... but it does show me it's possible.

not to get carried away, ... housing fish, being high enough on the food pyramid makes things that much more complex, and "possible" becomes an 8 letter word instead of anything to do with an easy reality.


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## Mikaila31

A year isn't hard, but I think I mentioned that before. Especially with things like snails, nematodes and planaria which are harder to kill then to keep alive. That doesn't mean it is self sustaining. Gradual build ups or losses of nutrients can take a long time to effect the system and especially the highly tolerant organisms in them. There is a common ecological method of assessing water quality of streams/lakes based on invertebrates, since they are effected by changes and quality. Snails are on the very low end of 'tolerant' invertebrates and not something you want to see a lot of in a natural ecosystem. 

pH and snail shells doesn't mean much, I have a ton of MTS in low pH. 

So the possibility is debatable regardless, but knock yourself out.


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## jaysee

agent13 said:


> and i'll have learned while watching your shenanigans flear >.<
> 
> i do enjoy watching your threads even if i don't always comment . Tis a great arena to learn odd bits and pieces .
> 
> 
> sent from petguide.com app



+1


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## Flear

yes, i've heard malaysian trumpet snails are ... almost impossible to kill

surviving temperature ranges that would cook other critters
surviving salt levels that are almost on par with marine tanks

the critters just don't die it seems
combined with their self-reproductive nature, ... if you have one you have a thousand.

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the greenwater in that bowl turning yellow has me concerned, i don't know what's going on, from other buckets of greenwater i have had, yellow can be too high nutrients and it can be too low nutrients, ... so i only add water to top up evaporated water, ... which in turn means adding lime and phosphates and whatever else is in tap water, ... 

if the greenwater crashes i wouldn't mind seeing whatever else is going on in that bowl though , currently only being able to see a 1/2" inside leaves the rest of what's going on a total mystery.

the micro-worms having dissapeared adds to the mystery, ... the greenwater going yellow, ... i do hope it crashes just so i can see more of what's going on inside. but as it's been going on this long without any changes, i don't see that happening, ... the bit of hair algae seems to be surviving, i'm holding out that over time it will win out, ... 

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even with the added nutrients from the tap water, i am not seeing any calcium deposits on the duckweed, so i don't think the calcium levels are excessive yet (that was going on in the main tank for a bit - hmmm, pH was being buffered at 7.0 at the time, hmmm, things to keep in mind)

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i was surprised to find in my searching online that duckweed and wolffia are both used in the scientific community to test for nutrients and toxins in a lake or similar for their ability to take in everything.

yet i can't find wolffia to buy


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