What's the point of water changes, really!?

[JackBlasto]

Just to make a quick statement. I started this thread NOT because I was neglecting my fish. My fish are in very good care with regular water changes. I only posted because I wanted a scientific breakdown on what was happening behind the scenes as a fish lived in water and what "built up" in that water. No fish are being harmed in my case. I wanted an explanation and I appreciate the info that has been given.

 

[Fresh2o]

Just to make a quick statement. I started this thread NOT because I was neglecting my fish. My fish are in very good care with regular water changes. I only posted because I wanted a scientific breakdown on what was happening behind the scenes as a fish lived in water and what "built up" in that water. No fish are being harmed in my case. I wanted an explanation and I appreciate the info that has been given.

Did not suspect neglect was a factor at all. Interesting thread with informative point/counter point responses.

 

[Delapool]

Would love to know of a test - I guess fish keeping is not black and white. Interesting topic. In my case I have increased water changes as I increased the fish count to fully stocked (freshwater tropical community tank). There was no science, I just increased until the water/gravel looked good/clear again. I started with 10% every fortnight and do 20% every week now. Can't defend it, just seems to work with the setup. Also in my case the tap water is ideal to stop ph,etc drift (almost!).

 

[GodFan]

Would love to know of a test - I guess fish keeping is not black and white. Interesting topic. In my case I have increased water changes as I increased the fish count to fully stocked (freshwater tropical community tank). There was no science, I just increased until the water/gravel looked good/clear again. I started with 10% every fortnight and do 20% every week now. Can't defend it, just seems to work with the setup. Also in my case the tap water is ideal to stop ph,etc drift (almost!).

There have been test done to see how it works. Honestly there is no reason to defend your pwc schedule! Some people do them more than others. My argument is not that you are wrong for doing them but that neither side is wrong.

 

[aqua_chem]

20%/week seems fine to me for a reasonable stocked tank.

 

[Wy Renegade]

I think this was jacks point, if your plants uptake dangers like nitrates, then what's the point? But like said before, it's necessary to replenish trace minerals, etc., not only for the plants, but the fish use them to be healthy as well. I know for a fact that jack is mixing his own water so would top offs be enough to replenish what the fish need to stay healthy for an extended period of time? I know a lot of salt tanks go years without water changes, I've just never heard of it positively discussed on the FW side. Seriously, thanks jack, this is a great topic to discuss and learn from.

Lets start here ~ as saltwater keepers have known for years, while plants or algae may uptake nitrates, they do not remove them from the system. The only way to effectively remove these nitrates is to remove the algae/plants which are uptaking them. If these algae/plants are not removed, and you experience plant die-off in your tank, which we all do even in a healthy tank, then those nitrates are released back into the system as the organic matter breaks down.

First off NitrItr should NEVER build up or you need to cycle your tank. Second off we have exempted discus and other sensative fish from theis repeatedly. Also in most cases those other unused toxins can be adequatly controlled by doing a water change every few months! Barring extreme circumstances we should all be able to do once a month pwcs on our planted tanks.

Again, this is an incorrect. Salt tanks which have run for years often suffer from a syndrome known as old-tank syndrome. Studies show that nitrate is uptaken by both sand and rock, and as the sand and rock breaks down those nitrates are released back into the system. There are in fact lots of conditions in which nitrates can and do build up in a system.

Thats easily an exaggeration. My tanks lose around 5g of water from the 55s and 10g from the 150 just because of it evaporating. You can not keep an oscar in a 10g tank with no water changes or top offs longer than 8months without it dying. And even 8 months would be h one earth for said oscar.

Agreed, no Oscar can be kept in a 10 gallon tank for years and be happy, but this has already been addressed and answered.

After doing a 50% water change, the next day ammonia was at .25... Not sure.

On the bright side, i found out that a local aquarium company gives out FREE RO water. They say you can bring a tub and get as much as you want...

It is possible to keep a saltwater fish-only tank without waterchanges, correct?

Not typically ~ people tried this for years and years when the hobby first got started. Part of why saltwater fish had such a reputation for being hard to keep alive. Frequent water changes is pushed much harder on the saltwater side now days than on the freshwater side.

Truth is, people have been keeping fish in captivity for lots of years without doing water changes, and in their opinion with success. The real question in my mind has to focus on what we are going to call success. Many of us in the hobby measure success in terms of a few months or a few years. Research shows that many fish can live not for a few years, but for many years. True success in my mind is measured by being able to actually keep fish alive for the length of their entire life span.

This statement is untrue. The only thing being evaporated is the water, so anything that is dissolved in the water becomes more concentrated. You can top the water back up, but the original amount of TDS is still there, and will keep increasing, despite regular top offs.
The only way to reduce TDS is to physically remove them from the system via water changes.

Obviously true, and as has already been pointed out, there are many things that continue to concentrate within your system from various sources ~ including the food that we feed. The simple truth of the matter is that there are far greater and far more stories about people keeping fish successfully with more frequent water changes than those few that exist about people keeping fish successfully with no or infrequent water changes.

There have been test done to see how it works. Honestly there is no reason to defend your pwc schedule! Some people do them more than others. My argument is not that you are wrong for doing them but that neither side is wrong.

Agreed - truth is I have tanks that I do regular frequent water changes to and tanks that I do infrequent water changes. In part, I think that the rate of water changes needs to be driven by the individual inhabitants of the tank and the system itself.

 

[PerfectDepth]

My $.02

I like to keep a regular water change schedule whether I need to remove nitrates or not. Why? Simply because I like to keep my tank water as similar to my tap water as possible.

Keep in mind that in an emergency situation, a large volume water change is usually the best solution. If you don't change water regularly, it's more likely that a sudden large volume water change will cause undue stress for your fish or even osmotic shock.

 

[Billbug68]

Lets start here ~ as saltwater keepers have known for years, while plants or algae may uptake nitrates, they do not remove them from the system. The only way to effectively remove these nitrates is to remove the algae/plants which are uptaking them. If these algae/plants are not removed, and you experience plant die-off in your tank, which we all do even in a healthy tank, then those nitrates are released back into the system as the organic matter breaks down.

So you're saying plants and algae uptake nitrate and store it, rather than use it as a nutrient contributing to growth? Is this correct?

BTW, I'm not advocating no or infrequent water changes. I'm simply exploring the science and or proof behind the necessity if we exclude nitrate as a factor since plants are using it to grow. Again, really, I'm not looking for answers or opinions on nitrate, I'm asking WHAT ELSE builds up in the water that is NOT removed by healthy plants, that is still harmful to fish? That's all I want to know...

 

[molliwopp]

Im not going to read every single post on the thread because its already 5 pages long but i will say in my mind regular water changes are nessesary for afew reasons.

The minerals in the water will be depleated by plants inside the tank, making the water mineral deficient quickly. If my memory aerves me correctly this can effect kh or water buffering properties.

Surely the water would become loaded with microscopic particals of God knows what, particals from the air and anything else would then gets held inside the tank. Not good.

There are definitely positives for regular water changes and your fish deserve it. Can it be done, yes. Fairly? No i dont believe so, not without some expensive water filters, purifing equipment and remineralising equip.

 

[GodFan]

Renegade fair assesment. However I have 2 things. First of all nitrite should never build up in your system. Nitrate yes. I think you missunderstood my last post about that.
Also plants do not store nitrate. They use it to grow. Just like we dont store oxygen. We inhale what we need and exhale everything else plus co2. Plants dying will add nitrate because it is another thing breaking down into ammonia, then turned to nitrite, then nitrate.

Im not going to read every single post on the thread because its already 5 pages long but i will say in my mind regular water changes are nesssesary for afew reasons.

The minerals in the water will be depleated by plants inside the tank, making the water mineral deficient quickly. If my memory aerves me correctly this can effect kh or water buffering properties.

Surely the water would become loaded with microscopic particals of God knows what, particals from the air and anything else would then gets held inside the tank. Not good.

There are definitely positives for regular water changes and your fish deserve it. Can it be done, yes. Fairly? No i dont believe so, not without some expensive water filters, purifing equipment and remineralising equip.

That is a common misconception about planted tanks with infrequent water changes. The minerals will be depleted however top offs will add them back in. Wih the exception of high light high tech or especially needy plants this should be plenty.
I KNOW it can be done fairly as I have done it and know of others who have as well. The fish didnt just survive they thrived!

 

[molliwopp]

Renegade fair assesment. However I have 2 things. First of all nitrite should never build up in your system. Nitrate yes. I think you missunderstood my last post about that.
Also plants do not store nitrate. They use it to grow. Just like we dont store oxygen. We inhale what we need and exhale everything else plus co2. Plants dying will add nitrate because it is another thing breaking down into ammonia, then turned to nitrite, then nitrate.

That is a common misconception about planted tanks with infrequent water changes. The minerals will be depleted however top offs will add them back in. Wih the exception of high light high tech or especially needy plants this should be plenty.
I KNOW it can be done fairly as I have done it and know of others who have as well. The fish didnt just survive they thrived!

Top offs will add them back, yes but correct me if im wrong but wouldnt this also raise general hardness? Because the minerals that arnt being used would build up?

 

[duromega]

this is a joke

 

[dwayne.aycock]

Wow......we remain steadfast in our beliefs despite overwhelming factual data that water changes are both a requirement and a quality of life issue. As stated before, things that build up in the water column that are not motabolized by bacteria, suspended by filtration, absorbed or neutralized by plants, or rendered harmless in the presence of light, are STILL in the tank and continue to increase over time. These compounds must be physically removed from the tank. Some compounds are harmless in small increments, but become hazardous in concentrated amounts. Others have a synergetic effect when combined with compounds from plants, other life forms like nematodes, or anaerobic bacteria to result in catostrophic consequences. I still do not get the logic when asked "why are water changes necessary" in the face of overwhelming imperical, factual and observational data.
D

 

[molliwopp]

this is a joke

To be blunt, your post is. If youve nothing on topic or interesting to say, dont. This is an interesting discussion and what the forum is here for.

 

[GodFan]

I think the title of the thread is turning people off. The op was simply asking for the scientific reason we do water changes besides nitrates. He is not bad mouthing PWCs.
Alright so the science is this: there are other compounds that plants cant take out. We need to change the water because of this. HOWEVER we do not need to be so stringent in the frequency. Honestly I do not know how or why somebody decided a once a week pwc was mandatory. Just like the inch per gallon rule it is a false blanket statement that may be true in some specific circumstances but as we have already observed it wouldnt work for discus and while it will work in a planted tank it isnt always necessary.

 

[Cactuspixie]

I think the title of the thread is turning people off. The op was simply asking for the scientific reason we do water changes besides nitrates. He is not bad mouthing PWCs.
Alright so the science is this: there are other compounds that plants cant take out. We need to change the water because of this. HOWEVER we do not need to be so stringent in the frequency. Honestly I do not know how or why somebody decided a once a week pwc was mandatory. Just like the inch per gallon rule it is a false blanket statement that may be true in some specific circumstances but as we have already observed it wouldnt work for discus and while it will work in a planted tank it isnt always necessary.

Well I can only speak for myself. My tanks are heavily over filtered, lightly to moderately planted, not overstocked and do best with two water changes each week.
When I was only doing one a week I was having problems with my water chemistry, the water didn't stay crystal clear- I hate a tank with visible particulates in the water. I don't know my fish's opinion on them
My fish seem to enjoy water changes- they love the disturbance of the substrate and the influx of fresh water. They are most active the first two days after a pwc.
I was reluctant at first to change so much water so often, because we have water restrictions here, and water is expensive (out of the tap). And with 6 tanks its time consuming, but it is part of the hobby, and I've learned to enjoy the interaction with my fish and creating some interest in their environment (I usually move a few things around)
For me, the biggest worry in not doing frequent water changes (given the use of specialized media to remove nitrates) is the tank becoming unstable.

 

[Cactuspixie]

Plus in the summertime its the best way for me to keep water temps down- I do additional small daily changes at the peak of summer.

 

[Caliban07]

I think like this. 'What harm can a water change do to my fish' nothing 'what harm can not doing water changes do' I don't know = do the water change.

I think build up of nitrates depends entirely on your tank and this is why it works for some and not for others. Number of stock, types of stock, bioload produce, size of tank, sufficient bacteria, plants, feeding habits, food types etc

In other words a fully cycled 5 gal tank with 5 goldfish, no plants fed three times a day will result rapid nitrate build up as opposed to a fully cycled 55g tank with 8 medium fish fully planted fed once a day will take a lot longer for nitrate build up and you could probably wait longer in between water changes because of dilution. Dilution of toxins and addition of minerals that are found in our tap water is my reason for water changes.

An open body of water that contains life will always have fresh water coming in from somewhere. Rain water, ice, snow. Fresh water comes from somewhere in the wild and that's what we are trying to mimic. But these bodies of water are so vast in comparison that constant dilution prevents toxins from becoming harmful. Our body of water is a small cube.

Put a human in a warehouse and stop all source of oxygen. It's not the lack of oxygen that will kill us. It's the build up of exhaled carbon dioxide that will poison us. Put the same human in a cupboard with no oxygen source and they won't live nearly as long. Unless we dilute the air with more oxygen.

Water changes don't just add minerals for our fish they also add minerals and micronutrients for our bacteria too.

Phosphate block is an interesting phenomenon. There's an article on the web.

 

[Delapool]

That was my case. I need to do 20% water change a week now to keep my kH from decreasing (I see this has been an active thread overnight ?). Also to keep my gh from increasing and keep the water clear. I can't get any more fish as fully stocked (sigh) but if I did then my water specs are close to the fish shop tanks. The rosy barbs do seem active afterwards.

 

[Sillyfishies]

This question still hasn't been answered. Aqua_chem is the only one who has been close to answering this. What "trace" toxins build up? Scientifically why do we need water changes. Not theoretically.

I'm pretty sure we all understand water changes are good. But why is less frequent water changes so bad, in a heavily planted tank.