How do you know when a tank is a self contained ecosystem?

M

MadSkillzMan

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Nov 28, 2005
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hi guys. ive red on a few sites, that people have planted their tank to such an extent, that they dont even vac or waterchange it, that the plants take care of all the crud underneith, as well as the nitrates, and the only water they mess with is topping off

So ive hit this point that after a few days overdue for my waterchange, nitrAte is only 10mg/l...usually i dont know what it is, i just got a test kit for my SW tank, and ive been busy w. that to clean this tank

it actually should be higher, to keep my phosphates down and my BBA away..but the CO2 is doing a good job at cancelling out the BBA

now someone on here told me thatif i stopped waterchanges, id be leaving out some essential elements that come into my tank with the new water...is that true? or could a simply supply it via ferts such as KO3 etc?

so what im wondering is, how do i know when ive hit the point where everything is taking care of itself, not requiring the weekly changes and vacing? cause otherwise i have to uproot everything and clean out A TON of junk

i hope this is the right section. Thanks in advance guys
 
I don't think you will ever truly be able to achieve a self-contained ecosystem in an aquarium. Lakes and rivers are constantly be recharged with new water from run off and groundwater. The natural hydrological system is quite complex and life surface water depends upon the constant flow of water in and out of the system.

By not changing the water, it allows chemicals to build up in the aquarium and create problems for the fish and plants. I'd advise you to keep up with the water changes. Even if you miss a change or two, it's better to have some water changes than none at all.
 
Diana Waldstad advocates no (or more accurately, rare) water changes. Many folks follow her lead. I do not. Nitrate is only one pollutant, which we can easily measure. Minerals will be removed below needed levels, while others will build up. Just topping off without reset partials will increase the TDS of the water, while allowing the KH to be depleted. If you want to test for all nutrients which the plants require, I promise you that it will cost you a lot more time and money than just changing the water regularly.

The balanced aquarium is still a myth IMHO.

You have a balanced ecosystem when you add no food, no CO2, no plant ferts, and your plant mass and fish mass remains stable over long periods. If you are adding anything, or removing anything, it is not a balanced system.
 
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RTR said:
Diana Waldstad advocates no (or more accurately, rare) water changes. Many folks follow her lead. I do not. Nitrate is only one pollutant, which we can easily measure. Minerals will be removed below needed levels, while others will build up. Just topping off without reset partials will increase the TDS of the water, while allowing the KH to be depleted. If you want to test for all nutrients which the plants require, I promise you that it will cost you a lot more time and money than just changing the water regularly.

The balanced aquarium is still a myth IMHO.

You have a balanced ecosystem when you add no food, no CO2, no plant ferts, and your plant mass and fish mass remains stable over long periods. If you are adding anything, or removing anything, it is not a balanced system.
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Very well-put. I'd also add that IMHO it would be impossible to even consider a long-term truly balanced, self-sustaining system in anything less than thousands and thousands of gallons.

I guess you could say that even the oceans themselves aren't self-sustaining in that gravitational pull from the moon and the tides it creates is an important source of movement and energy that helps keep them from stagnating.
 
I have a 10 gallon tank where all I add is food.

The lid prevents water from evaporating so I've almost never done water changes.

The plants are: anacharis, java moss and java fern.

I keep bluefin killifish and feeder guppies in it. Some snails are present also.
 
My grandparents have a tank that they've had going for as long as I can remember, at least 20 years. No water tests, water changes, or artificial lighting at all. All they do is feed fish and top the tank up now and then with aged tapwater. They keep guppies in the tank and they also add a new guppy each year to decrease inbreeding.
And the tank really is very pretty and about as self-sufficient as a tank can be. They have lots of some kind of Vallisneria in the tank, lots of little red snails, and some sort of algae the grows in little 'puffs' on the bottom (very pretty for an algae, and a good hiding place for baby guppies). The snails keep the plants and glass clean.
 
My grandparents have a tank that they've had going for as long as I can remember, at least 20 years. No water tests, water changes, or artificial lighting at all. All they do is feed fish and top the tank up now and then with aged tapwater. They keep guppies in the tank and they also add a new guppy each year to decrease inbreeding.
And the tank really is very pretty and about as self-sufficient as a tank can be. They have lots of some kind of Vallisneria in the tank, lots of little red snails, and some sort of algae the grows in little 'puffs' on the bottom (very pretty for an algae, and a good hiding place for baby guppies). The snails keep the plants and glass clean.
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fish can build up an immunity to the raising toxin levels in water over time. Guppies are a pretty hardy strain no? so the current fish though having a depressed immune system and overall health survive through slow aclimation while the new guppy added each year gets quite a shock when dropped into this nasty water. i wouldnt be surprised if this is whats happening, opposed to a contained ecosystem.
 
I response to the guppy post, I know that endlers were first discovered in a stagnant pond on the site of a waste dump. So we know guppies will survive in basically a toxic cesspool. Tanks being inside the house and all, I think that adds to the necesity of water changes. Indoor air is full of chemicals from cleaners and air refresheners. Just thinking about that alone building up over time would make me want to do a water change. Even if your nitrates are kept down by the plants, u have to worry about dissolved solids. There are entries about how these dissolved solids can wreak havoc on many aspects of your aquarium water like the PH and the health of your fish. If you have a planted tank, which u would need for a self-contained system, water changes replenish some micronutrients and remove others that have built up too much. I know a self contained system is possible but I think the benefits of water changes outweigh trying one. Its always a good idea to create a system taht works so well that u could go without doing water changes for a while... yet still do the water changes anyways. My brother bought a paperweight a couple years ago. Its a self-contained sealed glass orb. Inside it water, gravel, algae, and cherry shrimp. You cannot feed them, u cannot change the water. They have been alive and well for 2 years now.
 
Back to the early statement, I believe the better phrase is not 'self-contain' but 'minimal maintenance' system, relatively of course. Another related term is 'low cost' but it is already out of topic.
BTW, I pity that paperweight cherry shrimp.... for the sake of temporary 'self-contain' system.
 
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