Is it possible to never have to do water changes in my aquarium ?

If you ask anyone, from the big box aquarium store employee to the often quoted internet forum guru, is it possible to never have to do water changes ? The answer will almost always be, yes you must do water changes.

For the average aquarist, this is good practice. We cannot control or monitor all the parameters in our open water system so this makes the most sense; to change at least 10% to 25% of the water each week, presumably due to nitrogen by-products and fish waste. As well, we assume that we understand that the fish we keep, excrete the same amount of waste, but in our minds we know that goldfish versus tetras are a world of difference when it comes to feeding and waste. For these reasons it is a general undertaking that this is good practice and certainly does not do any harm, only benefit.

On the other hand, a fully planted aquascape with CO2 and technology built around a nitrogen feeding understanding by advanced aquarists, may never need to ever to do a water change. Amano most likely had this in mind as a truly balanced aquarium ecosystem where plants were the central and focused biological engine to convert nitrogen into useful nutrients. What better could be accomplished if one were to truly master and harness this engine ?

For fish breeders, I change my water each week but I get lazy and perhaps extend every 10 to 14 days. Do my fish still breed? Yes. I also have tanks full of blue green algae.

For most hobbyists weekly water changes has been a good practice, and good hygiene. If you are not doing this, you are increasing the risk of health issues or disease, or as so many experts say. In practice, many experienced and successful breeders change water every week and they are a testament to this well accepted adage. Scientifically I do not think this concept has ever been proven, but it makes sense.

Well, what has been your experience? My opinion is that you should continue to do weekly water changes.

One simply had to follow up on Amano's beautiful installations, and try to find them two years later. In theory, with technology, no water changes were possible, but in reality, tanks are just big puddles that are too small to balance. The balanced aquarium's a myth many have chased for decades.

I sometimes think the best research an aquarist can do is to go the countryside and stand in a stream. Look at it. Feel the water movement. Then stand in a few more streams and think about what they are. Then go home and do water changes....

I guess in theory if one could obtain a perfectly balanced aquarium water changes would not be necessary. That however as mentioned is a dream for most left unchased. Even if you were able to come close to the perfect system, why risk it. Water changes are the perfect bit of insurance that is pretty much fool proof.

I personally do massive water changes every Saturday to maintain the water conditions in my tanks. I have huge bio loads and no plants in my systems to rid them of Nitrates. Even with the oversized bio filters I use, it's just not worth the risk to my fish.

As the old saying goes "The solution to pollution is dilution".

Now for me outside is a different story. In my ponds I come as close to a balanced system as you can get in a non-natural setup. Once my ponds are setup for the season, I don't do any water changes. It obviously does rain and the ponds will overflow slightly over the summer but not by much, it mostly just accounts for the evaporation. So I have 40 fish, some quit large in about 2,000G of water that remains perfect all summer. These fish are feed as much as 5 times a day during the warmer months. So with adequate bio filtration and massive amounts of plants I seem to have found the correct balance. Over the years I have kept a close eye on my water parameters, but now I can pretty much tell how things are going by looking at the plants. If the water hyacinths are growing mad and taking over the place my nitrates are probably high. If they are looking kind of pale, then I am in good shape.

So I am a big believer in doing regular water changes in your home aquarium. Even if you think you have achieved the perfect balance it’s just a safe practice to follow.

Steve

My religious 30% weekly water changes have already cost me several wild bettas even though I match the water temperature. So, as we say in Dutch: don't comb all hair with the same comb!

There are exceptions! Now that I am doing less water changes and smaller ones, the fish thrive.

Ah, but the word here is "never".
I do all Cichlid, livebearer and rainbow tanks weekly.
With most killies except lampeyes, water changes stop all breeding for 3-4 days. So I do them every second week.
My Priapichthys seem to dislike big changes, so they get 10-20% weekly.
Growing young will thrive with changes every day. I don't have time, but if I can do them twice a week, I do.

You adjust as you learn, and as you move from maintaining to breeding attempts.

As an avid aquascaper, I feel I must do water changes to keep things neat and tidy.
It helps to keep algae at check and it helps lower my TDS,
When I don't do any water changes for more than 3 weeks, things start to go South.
Most plants will not enjoy hard water.
I guess that if you use only RO/DI Water you could get away with it for longer, but still, there would still be an issue with TDS.

The most I have been without a water change is three months on my 10 gallon tank and it was doing ok. But it only had a Betta fish in it and is filled with plants.

I agree with Gary, an aquarium with fish in it is not capable of balancing itself and needs frequent water changes.
You can get away with less changes depending on the size of the tank, the stocking rate and the kind of fish you keep in there. My goldfish tank needs a min. 40% water change every week to keep the nitrate in check, period! My 10 gal glowlight tank I can go with a 30% every two weeks and the frog tank I had 3 weeks with still very low nitrates. Maybe I could go even go 3 month like I_I_I but at some point the "polluted" water needs to be replaced with "fresh" water
Tell me if I'm wrong but even in closed natural bodies of water like lakes and ponds, even the man made ones, "water changes" are happening: Ground water rising and leaking into the pond, rainwater falling and washing in from the surrounded land. And then, when the water levels are high once or twice a year there is pond water "taken out" by overflow and seeping into the ground at the pond edges and shores (as Steve mentioned above in his ponds)
On the other hand, in our tanks we put tropical fish from different habitats into a, even if meticulous copied but still artificial small "glass framed section" of nature. It is missing processes like season changes and I personally also take in consideration all the other creatures that are missing in our tanks. From all kind of micro organisms to crustaceans to other fish and even native animals that are all playing a role, big or small in a balanced ecosystem.
So while a natural, healthy body of water does very well with a comparable small water change every year or two, I say our beautiful little man made sections of nature are so small and closed systems, they just need a man made filtering and man made water changes every so often.

For years I never did water changes, just added water to replace what had evaporated. That said, twice (sometimes once) a year I would remove everything from the tanks, give it a thorough washing, replace everything including about 25% of the water and add 75% new water. Fish did fine. Nowadays my tanks are overpopulated. So I will siphon the tanks every couple of months and change anywhere from 25 to 75% of the water (smaller tanks usually get a larger water change). Fish still do fine.  But there is no such thing as never changing the water. There is no possible way to establish a perfect environment in a tank, they are just too small. Unless... you have a large tank with loads of plants and not any fish to really speak of...

I've been across the whole range - no water changes when the myth of the balanced aquarium was popular, occasional water changes when the myth of myself as a careful aquarist was popular in my head, and weekly to monthly depending on the fish now.
I agree with Eleonore that weekly doesn't always work - swamp Bettas or licorice gouramis don't like change.

But since I became a little more organized (and my soft, not well buffered tap was an incentive), I have found better growth, fewer losses and healthier, longer lived fish to be the result. I think I am coming out on the right side of this hit or myth hobby.

I have a problem here with low nitrates, given my soft water, heavy planting and water changes - it gives me cyano a lot. I'm experimenting with lower water changes in affected tanks - I did 15% on a few yesterday. We will see.