Are Water Changes Actually Necessary?

[sorberj]

Ok, I have to jump in on this...but only for a little bit. The metaphor of "Aquarium as Ecosystem" fails because home aquarium just isn't big enough to support all of the processes that occur in the water cycle, let alone all of the other cycles (nitrogen, carbon, etc.) that take place on our planet. The ecosystem that our fish come from is much more broad and expansive than just a pond, puddle, or stretch of river bank. When the water enters the system, it is first distilled (i.e. evaporation), then subjected to UV sterilization in the upper athmosphere, it falls onto land, glaciers, etc, where it is mechanically filtered and then minerals are added to it (through erosion), it then starts growing life with the addition of sunlight, through many different environments. As that water flows downward, it typically warms and experiences several different combinations of dissolved solids and minerals. It's pH will change based on the geologic structres that it passes over, and different organic compounds will be broken down based on that particular chemical composition. Some solids will precipatate out through chemical processes or be filtered out and added in through biological processes. The water eventually makes its way into brackish estuaries where huge numbers of biological processes take place, and then back into the ocean where it is distilled again. It's not that the earth isn't a closed system (for the most part it is), it's that it's much more complicated, than can be provided, even given the different environments provided by a deep sand bed.

With all that said, the relative success of keeping an unchanged aquarium will depend on species (mollies, as given in one of the original examples) can handle brackish conditions and may actually do better in an environment with a higher level of TDS than a species that's a bit more sensitive like Blue Rams.

All of that aside, the reasons why I change water (about 30% per week) are:

1. I like to see my fish
2. I don't like the smell of an estuary in my home
3. I have plants and use ferts
4. I like to have the option of adding fish without having to acclimate them to water that has built up "stuff" over the course of years.
5. I don't use a UGF anymore since I went planted.
6. I know from gardening that if you don't rotate your crops (which you cannot do in an aquarium so you rotate the water instead), you will eventually increase your pest load which can lead to disease, and since I don't utilize a UV sterilizer, my pest load would build up.

 

[thorpbrian]

more like 99.99%

Yeah actually right after I posted I was thinking it was more like 99.99% also...

 

[mellowvision]

I voted for "when it is required" altough this will be a new way of doing things.
In the past, I too have thought regular weekly changes were the best way to go and have done that. As I learn more about this hobby I am questioning that theory and and going to try to not do as many water changes.
My reason for this is an ongoing battle with cynobacteria I think is due to low nitrates and plenty of friends bugging me about my water change schedule. (As in they do not do weekly changes either)
This is, and hopefully will continue to be, a very interesting thread.
Just wondering what large, public aquariums do about water changes. Anybody know?

The large public aquarium that I am involved with has strict water change regimines that go way beyond what is considered normal in a hobbyist's home. They do range from tank to tank, depending on the size of the tank, it's inhabitants, etc. But all tanks are regularly given water changes with water matched for it's inhabitants needs. I'll give you an example. A 120 gallon tank housing 1 Leaf Fish and it's feeder guppies is given a 50 gallon water change twice a week, with water that has been aged since the last change, heated, airated, with leaf litter and blackwater extract neccessary for the Leaf Fish's survival. They are very sensitive fish. Moreover, the tank's makeup water is also aged the same way, so that fish should never see a noticeable change in water quality. They are given what they need. It is unethical to not do this for them, if the aquarium is to keep them on display. Many tanks in the aquarium go even further, having a constant stream of makeup water that flushes the sump slowly but constantly.

I'm not sure what the debate here really is. The question posed is flawed to begin with. It's too broad. There is no possible way, short of a pond, for you to create a closed ecosystem at home. Adding more than light requires the removal of it's final outcome, be it plants that overgrow the tank, detritus on your glass bottom, or hormones, or salts, or whatever. I won't argue that you can't keep fish alive for 20 years in filthy water. You can. It's not how they live in nature, no matter what you might think. It's not how they'd choose to live, if given an option they would migrate to the most suitable water.

I guess my point is, if you choose to keep an animal captive anywhere but where it occurs in nature, you are ethically obligated to give it the highest level of care that you are capable of. Water changes are part of that level of care. And honestly, water changes from the tap are just barely cutting it... Most fish would prefer something different from the average tap.

What each individual knows and is capable of may be greatly different.... but I doubt that anyone here is incapable of doing a regular water change.

 

[Fishfriend1]

It was theoretical sheesh im dont think im going to post on this thread for a wile.

 

[sorberj]

I have a feeling that you might as well ask a bunch of mothers whether or not spanking is necessary. You'll probably catch just as much heat on either side.

 

[Fishfriend1]

lol

 

[Chrisinator]

Not sure if my thoughts have been covered but:

1. In aquariums with fish that come from higher pH (african cichlids and such), the pH will lower as old tank syndrome occurs. Plus, with plants, they can't help with nitrates due to the fact that african cichlids eat them up (unless your talking about Anubias or Java Fern.) But those plantss are slow growers and aren't gonna suck up much of the nitrates. Also, I think lower pH has effect on snail shells (which you'll probably need to clean algae) which could cause shell erosion and such.

2. In a planted aquarium, people use macro and micro ferts, and a build up of those would be too much. When you dose, you kinda dose for the amount of water you took out. Also, you seem to be considering things in terms of planted tanks. Not everyone keep planted tanks. People keep african cichlids, some people with fake plants, and salt water.

3. What about fish that get sick? You're just gonna let mother nature take it's course and let all the other fish get sick from it? You're gonna have to change the water to dilute the amount of "bacteria/viruses" and possibly eliminate the disease.

4. What about the build of up sediments? In a society where money is tight, not everyone is going to be able to buy that "Holy Filter" that just sucks up all the sediments. You don't want your poor old cories swimming in poop, do you?

5. When you talk about adding salt, have you considered fish such as Loaches and Corydoras? Neither can take salt because they are scaleless. Loaches just have skin and Corydoras are a little better with their armoured plating. It's always recommended not to add salt when keeping them.

In nature, (since we keep referring back to it), water is constantly doing "water changes". Rivers, lakes and streams (not sure of the ocean). Unless you want to flood your tank or hook it up to a river, you're going to have to sometimes do water changes.

I agree though that weekly might be too much for certain tanks, but the fish don't die because of the water change (unless you put freezing cold water, or hot water or you forget to dechlorinate it).

Just my thoughts.

 

[Inka4040]

Water changes are necessary because not doing them leads to the aesthetic decline of the tank. Because I keep my fish mainly for aesthetic reasons, water changes are necessary for me.

 

[kazvorpal]

what about me, i have too use tap water running through the pipes of a 60 yr old suburb?

should i then limit my water changes?
should i also be using activated carbon to get crap that may be running through my pipes?

Your old pipes might be terrible, or they might be wonderful. That's only the roughest of data for a starting point.

You definitely are better-off knowing the condition of your water. Even if you're not going to maintain fancy testing kids for years, you might want to get the water tested at the outset, so you know what you're dealing with.

Hopefully, if you're not talking about a marine tank, you can use the tap water, you just will need to know what, if anything, needs to be done to make it safe. Even dechlorinator can, for example, get rid of some heavy metals.

I don't drink tap water. The local government's proud announcement about how much lower the lead is than last year (when they didn't say anything at all) is a great example of why.

Don't even get me started on how state-mandated monopolies, like water departments, are bad for society.

 

[Inka4040]

"The people who speak out against the need for regular water changes are simply defending their own self righteous ignorance. They've heard they're wrong, but haven't seen the proof, so their laziness needs to be given reason."

Not sure where I've heard that, but it just fits so well.