Hypothetical Question

**ijankrom** · 11-30-2012, 07:43 PM

Listening to a podcast a listener asked a hypothetical question.

"If a home aquarium is large enough, bioload low enough, and filtering is strong enough, would it be possible to operate a aquarium without completing water changes?"

Put your thinking caps on - What would your answer be without having any further info?
If there's any remote possibility this could work, how would you imagine the system would be setup?

I'm sure many of you are thinking it, "how could I have a self sustaining system"?

**KingFisher** · 11-30-2012, 08:04 PM

No. Evaporation would cause dissolved substances to continuously build up over time until their levels became toxic to fish. Hardness would increase, ph would change, the tank would eventually crash.

**dbosman** · 11-30-2012, 09:18 PM

Originally Posted by KingFisher

No. Evaporation would cause dissolved substances to continuously build up over time until their levels became toxic to fish. Hardness would increase, ph would change, the tank would eventually crash.

Ok, add the caveat that water top offs will be made with RO water.
Next...

**KingFisher** · 11-30-2012, 09:20 PM

There would still be fish hormones etc... building up in the water, not to mention depletion of electrolytes.

**Dennis Bissett** · 11-30-2012, 11:27 PM

All the minerals and trace elements would also deplete - it would eventually become distilled water

**Honey Badger 1** · 11-30-2012, 11:32 PM

And nitrifying bacteria cannot live or reproduce in distilled water.

**4Mike** · 02-22-2013, 08:01 AM

I have read some are successful doing almost no water changes. Some go as long as a year or more, but eventually they end up doing a water change!!

**talldutchie** · 02-22-2013, 08:39 AM

With the walstad method you can get pretty close to a system where you have to do very occasional partial water changes and mostly just topping up.
http://www.theaquariumwiki.com/Walstad_method

It's just not very popular because it allows for much lower stocking densities than most of us prefer.

Diana's shrimp bowl is a great little experiment. All it requires is a small tank or fish bowl, a small air pump and stone for some water movement and some plants.
http://www.atlasbooks.com/marktplc/00388Shrimp.pdf

**Crispy** · 02-23-2013, 06:55 PM

even with a low bioload, nitrate doesn't break down on it's own. it needs to be removed via water changes. or you'd need alot of live plants to do this.

as stated above, valuable electrolytes, minerals, etc need to be replenished.

**Taurus** · 02-23-2013, 07:13 PM

Originally Posted by talldutchie

With the walstad method you can get pretty close to a system where you have to do very occasional partial water changes and mostly just topping up.
http://www.theaquariumwiki.com/Walstad_method

It's just not very popular because it allows for much lower stocking densities than most of us prefer.

I have a problem with the write-up of the article that is linked to above. Adding Prime or Amquel + to the aquarium water does not remove ammonia. That will temporarily turn ammonia into ammonium depending on pH. Neither remove ammonia from the tank water.

Even if there are enough plants in the tank to use up free ammonia or ammonium, water changes will still have to be done or the tank will develop "old tank syndrome." Minerals and\or electrolytes will be depleted, pH will vary greatly and the tank will crash.

Do yourself and your fish a favor by keeping up with regular water changes.