Reasons for water changes

[AJ356]

I'm more of a "I should change 40-50% a week" approach. I have no plants and already have 10-20 ppm Nitrate from source (tap water). I think if i had 0 ppm Nitrate, without plants, I'd still aim for 40-50% water change per week.

I'm not planning to reduce my water changes or looking for an excuse to reduce the percentage and frequency.
I'd just like to know some more science behind it, or even if you are not sure of the science, your own opinions.

Apart from "it feels like the right thing to do" why are we doing it? The first thing that comes to mind is that our fish are swimming around in their own pee, poo and vomit (to a degree). Do fish vomit? Maybe after a night out on the town, not sure? However, people who subscribe to the "I don't do water changes regardless of what other people tell me" always come back with "the plants" or "the ecosystem" takes care of it (Father Fish style?). I also believe "fresh" water probably has healing properties for fish, or encourages the healing process. Even if fish are not fighting, they can pick up knocks and scrapes.

I genuinely am not trying to reduce my own water change routine. I believe it's in the interests of my fish and set up. I'm just looking to (a) satisfy my curiosity and (b) having a somewhat insightful answer to anyway that asks why I aim for a 40-50% a week water change. In all honestly, I probably average 40% or 50% every 10-12 days.

Also, do plants absorb anything other than ammonia and nitrate in terms of them potentially reducing the need for water changes?

I do plan to do some wider reading and will post back anything of interest.

I know one "science" reason is minerals or "buffers" to help prevent a pH "crash". Father Fish gets round this by having a substrate that contains about 22 different ingredients I think, to keep things from going too acidic.

I realise loads depends on tank bio load and volume of water etc, etc, and etc x1000

 

[sharkweek178]

Many reasons. Diluting nitrates is just one. Water changes also replenish trace minerals, keep TDS low, help clear out pheremones and other semichemicals, remove pathogens.
Water changes aren't just to fix bad parameters (although they do that). A regular schedule of water changes keep your aquarium water stable so that they never get bad and you don't end up with old tank syndrome.
And if nothing else, the fish like it. Fish love clean, fresh water.

 

[Essjay]

I think Byron explains it very well in the sticky at the top of Tropical Discussion.

Regular Partial Water Changes

Byron Hosking November, 2010 (rev April 2021) Nothing is more important when it comes to aquarium maintenance than regular partial water changes. The adage “an ounce of prevention is worth a pound of cure” certainly applies here. One frequently reads of products that will reduce the need for...

www.fishforums.net

 

[FranciscoB]

I change 90-100% weekly, unless I am traveling. Would not have it any other way, and fish growing, thriving and breeding are my rewards.

 

[gwand]

I change 90-100% weekly, unless I am traveling. Would not have it any other way, and fish growing, thriving and breeding are my rewards.

How many gallons of water are you changing out weekly?

 

[GaryE]

I have zero nitrates in my tap water. I do a regular 40% (it has risen from 30%) every week if I can. I don't pass 10 days. All water changes for 50 tanks are logged on a whiteboard attached to the fishroom, door, and I have it down to an art. It goes quickly.

Why?

I never use test kits, and don't care about readings. I just change water, with the benefit of almost 60 years of fishkeeping and exposure to a lot of fads. If I compare the lifespan of my fish now compared to when I accepted what was once the orthodoxy, the no water change naturally balanced aquarium, I'm ashamed. I caused the premature death of a lot of fish through following unscientific methods. We all did as we didn't get scientific about water until the 80s. We didn't understand the nitrogen cycle, though we had observed it and had an inkling of both 'new and old tank syndrome".

I can now breed fish I could barely keep alive before. And changing some water once a week is a lot easier than taking the dog out at 6 AM during a snowstorm. I wouldn't think of not doing that as that would be cruelty to my dog to make her wait. It's similar with the fish - once it becomes a routine water changes are easy. You just have to do them if you have tanks.

I haven't seen fin rot in decades. I used to buy meds to treat it at least twice a year. I haven't had a stunted fry. Disease rates are way down.

We have to deal with pollution, hormonal chemical messaging, and a host of issues far beyond what test kits tell us. If I could, I'd do a water change every day.

 

[Colin_T]

This is my take on water changes and it's from spending years working in the pet industry (wholesale and retail fish) as well as keeping fish at home since the 1970s.

You need to do water changes regularly even if the water tests are good. There are lots of things in water that we can't test for and they need to be removed as well.

You do water changes for a number of reasons.
1) to reduce nutrients like ammonia, nitrite & nitrate.
2) to dilute disease organisms in the water.
3) to keep the pH, KH and GH stable.
4) to dilute nitric acid produced by fish food and waste breaking down.
5) to dilute stress chemicals (pheromones/ allomones) released by the fish.
6) to dilute un-used plant fertiliser so you don't overdose the fish when you add more.
7) to remove fish waste and other rotting organic matter.

Fish live in a soup of microscopic organisms including bacteria, fungus, viruses, protozoans, worms, flukes and various other things that make your skin crawl. Doing a big water change and gravel cleaning the substrate on a regular basis will dilute these organisms and reduce their numbers in the water, thus making it a safer and healthier environment for the fish.

Imagine living in your house with no windows, doors, toilet, bathroom or anything. You eat and poop in the environment and have no clean air. Eventually you end up living in your own filth, which would probably be made worse by you throwing up due to the smell. You would get sick very quickly and probably die unless someone came to clean up regularly and open the place up to let in fresh air.

Fish live in their own waste. Their tank and filter is full of fish poop. The water they breath is filtered through fish poop. Cleaning filters, gravel and doing big regular water changes, removes a lot of this poop and harmful micro-organisms, and makes the environment cleaner and healthier for the fish.

Whilst you might not have ammonia, nitrite or nitrate problems due to the plants in an aquarium, the number of microscopic organisms in your tank will be growing exponentially due to lack of water changes and this will eventually cause problems to the fish. Plants can't reduce the number of disease organisms in the water and plants can't fix water hardness or pH. Water changes can and should be done to dilute disease organisms and help keep the water chemistry stable.

If you do a 25% water change each week you leave behind 75% of the bad stuff in the water.
If you do a 50% water change each week you leave behind 50% of the bad stuff in the water.
If you do a 75% water change each week you leave behind 25% of the bad stuff in the water.

-------------------

For the OP, if you put some floating plants in your tank, they will help keep the nitrates down so in the event you are unable to do a water change one week, the water quality won't deteriorate as much. It's more of a backup for your water change regime just in case something happens. Floating plants like water sprite and duckweed do well in most tanks.

 

[AJ356]

This is my take on water changes and it's from spending years working in the pet industry (wholesale and retail fish) as well as keeping fish at home since the 1970s.

You need to do water changes regularly even if the water tests are good. There are lots of things in water that we can't test for and they need to be removed as well.

You do water changes for a number of reasons.
1) to reduce nutrients like ammonia, nitrite & nitrate.
2) to dilute disease organisms in the water.
3) to keep the pH, KH and GH stable.
4) to dilute nitric acid produced by fish food and waste breaking down.
5) to dilute stress chemicals (pheromones/ allomones) released by the fish.
6) to dilute un-used plant fertiliser so you don't overdose the fish when you add more.
7) to remove fish waste and other rotting organic matter.

Fish live in a soup of microscopic organisms including bacteria, fungus, viruses, protozoans, worms, flukes and various other things that make your skin crawl. Doing a big water change and gravel cleaning the substrate on a regular basis will dilute these organisms and reduce their numbers in the water, thus making it a safer and healthier environment for the fish.

Imagine living in your house with no windows, doors, toilet, bathroom or anything. You eat and poop in the environment and have no clean air. Eventually you end up living in your own filth, which would probably be made worse by you throwing up due to the smell. You would get sick very quickly and probably die unless someone came to clean up regularly and open the place up to let in fresh air.

Fish live in their own waste. Their tank and filter is full of fish poop. The water they breath is filtered through fish poop. Cleaning filters, gravel and doing big regular water changes, removes a lot of this poop and harmful micro-organisms, and makes the environment cleaner and healthier for the fish.

Whilst you might not have ammonia, nitrite or nitrate problems due to the plants in an aquarium, the number of microscopic organisms in your tank will be growing exponentially due to lack of water changes and this will eventually cause problems to the fish. Plants can't reduce the number of disease organisms in the water and plants can't fix water hardness or pH. Water changes can and should be done to dilute disease organisms and help keep the water chemistry stable.

If you do a 25% water change each week you leave behind 75% of the bad stuff in the water.
If you do a 50% water change each week you leave behind 50% of the bad stuff in the water.
If you do a 75% water change each week you leave behind 25% of the bad stuff in the water.

-------------------

For the OP, if you put some floating plants in your tank, they will help keep the nitrates down so in the event you are unable to do a water change one week, the water quality won't deteriorate as much. It's more of a backup for your water change regime just in case something happens. Floating plants like water sprite and duckweed do well in most tanks.

Thanks Colin, good points.

I've been thinking about floating plants, but not sure I even have enough lighting for that, as I keep my lights on an adjusted lower intense setting as I believe that's better for the fish than the very bright lights I've needed in the past for planted tanks.

 

[GaryE]

Thanks Colin, good points.

I've been thinking about floating plants, but not sure I even have enough lighting for that, as I keep my lights on an adjusted lower intense setting as I believe that's better for the fish than the very bright lights I've needed in the past for planted tanks.

I'm a fish first aquarist. There's a magic to floating plants (since the no water change people shouldn't have a monopoly on looking for magic). When they take off, intense light is cut by them. The aquascaper tanks we see rarely have a great tangle of floaters on their surfaces. But a lot of healthy tanks do. The floating plants provide shade, as do broad leafed plants like Amazon swords or Crypts rooted in the substrate.

I keep fish from dark habitats where no plants grow - streams under the forest canopy. I've caught fish in Africa, in lighting I wouldn't have been able to read in at mid day. I get your concern about intense lighting. But you can increase your lighting enough to give you the positives floating plants do, and the plants will ease the brightness.

 

[Essjay]

I have red root floater in both my tanks. In the main tank the filter outflow keeps the plants at the opposite end of the tank and there is a noticeable difference between the brighter filter end and the dimmer opposite end. The plants grow so well that between water changes they cover most of the surface and the whole tank is noticeably brighter after I remove handfuls during the water change.

I first got floating plants years ago after I noticed the whole shoal of one species never came out from the back corner. After I put the plants in - water sprite at the time - the fish started to venture out from the corner but only as far as the edge of the plants. As the plants covered more and more surface, the fish came further and further into the tank. Whether this was because the plants reduced the light or because they gave a fish a roof over their heads I don't know, but the fish were much 'happier' with floating plants.

 

[GaryE]

I first got floating plants years ago after I noticed the whole shoal of one species never came out from the back corner. After I put the plants in - water sprite at the time - the fish started to venture out from the corner but only as far as the edge of the plants. As the plants covered more and more surface, the fish came further and further into the tank. Whether this was because the plants reduced the light or because they gave a fish a roof over their heads I don't know, but the fish were much 'happier' with floating plants.

My read on this comes from replaying a video I shot in Gabon. When I played it back 2 years later, I realized the songs of birds in the background were constant, and loud. I had tuned that out in my memory. How many of those birds were fish predators? Judging from the way the fish behaved, a few.
Epiplatys killifish have even evolved what may be a third eye/light sensor on the top of their heads. It seems to detect shadows and light, and for these surface feeding insect eaters, would be invaluable for warning them against fishing birds.

We rarely saw any small fish (and not many large ones) in the open water. Life was lived under overhanging bushes. So we veer from water changes, but for overall tank health, shade and shadows are really important. You can even argue that water changes replace depleted minerals the essential floating plants need (essential depending on what species of fish you like).

I have mineral poor water, and that effects what plants I can grow, but since I don't add ferts to the water column, I find growth better with water changes. Yes, fish wastes are fed on by plants, but they also need minerals. So water changing affects fish behaviour as part of the complex system of a simple little aquarium, if you design the tank with the fish in mind.

 

[AJ356]

I'm a fish first aquarist. There's a magic to floating plants (since the no water change people shouldn't have a monopoly on looking for magic). When they take off, intense light is cut by them. The aquascaper tanks we see rarely have a great tangle of floaters on their surfaces. But a lot of healthy tanks do. The floating plants provide shade, as do broad leafed plants like Amazon swords or Crypts rooted in the substrate.

I keep fish from dark habitats where no plants grow - streams under the forest canopy. I've caught fish in Africa, in lighting I wouldn't have been able to read in at mid day. I get your concern about intense lighting. But you can increase your lighting enough to give you the positives floating plants do, and the plants will ease the brightness.

Thanks. Good point about the floating plants taking away from the intensity of the light for the fish.

 

[TwoTankAmin]

Floating plants make it harder to net fish and harder to feed flakes or other floating foods. Floaters are able to outcompete other plants for nutrients and, yes, they do shade whatever is below them as they cover the surface.

One more comment re water changes. I have yet to hear of any fish being killed because their water was to clean. By this I do not mean too pure but rather free of contaminents and other potentially nasty things that might build up in a tank where water changes are not done frequently. The easiest wat to understand this is in a salt water tank. If water evaporates is leaves the salt behind as salt does not evaporate. So if the SW keeper tops off their tank with more salt water, the salinity increases. They normally use RO or RO?DI water for topping off.

There are other minerals in the water which also do not evaporate. This applies to fresh water as well as to saltwater.

 

[Essjay]

The main reasons I have red root floater are that the plants are small, don't tangle together like water sprite and don't have long roots which tangle in the lower plants like Amazon frogbit (I've tried both). It's easy to blow a gap in them to add food. And they don't get in the way of netting fish, they just stick to the outside of the net when lifting it out. The downside is that they don't have lots of roots or grow into a thicket for fish to hang out in.
Salvinia is similar in these respects but it just died on me while red root floater thrives.

 

[emeraldking]

I myself am doing lesser water changes than an average aquarist. But that's because my tanks are well balanced. And in such a case less water changes are needed.
But in general. there's no specific amount of water changes per moment or even the frequency of it as a rule. For it depends on multiple factors. There are fish that thrive better when the tank is a bit polluted, there are fish that prefer less till none pollution in a tank. Same goes for plants. is there a sick fish? Or is the tank troo polluted. Or is there a lack of oxygen in there? Do you want fry to grow up faster? And so on...

I've got a number of fish that don't thrive well when too many water changes is in play. These thrive well in dirted water and even reproduce better in there.