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

[GodFan]

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.

It isnt bad. I would be interested in knowing what exactly builds up as well. I know certain fish dont seem to like it so I what is it?

 

[azmodan]

Watch for signs of stress first off. My red cherry shrimp are breeding which they woukdnt do in adverse conditions. It isnt that hard to do. We all do it.

I guess my point is that I find it very hard to say that certain fish/inverts are happy just because they are not stressed and reproducing. When I was younger (and not at all knowledgeable) I remember having a pair of mollies breeding in a tiny filtered 2 gallon tank that could not have been very clean. I've also had RCS breed in similar situations as they are quite prolific. Are they alive and reproducing, you bet. But happy and healthy? I'm not so sure on that one. In most cases that's impossible to measure on a relative scale with such upmost certainty. I should note that this is more in response to generic species commonly found (such as RCS), as naturally one would get more specific indicators with sensitive creatures such as CRS and discus. Sorry, I know that's not quite the topic on hand but just wanted to mention that perspective.

 

[GodFan]

I guess my point is that I find it very hard to say that certain fish/inverts are happy just because they are not stressed and reproducing. When I was younger (and not at all knowledgeable) I remember having a pair of mollies breeding in a tiny filtered 2 gallon tank that could not have been very clean. I've also had RCS breed in similar situations as they are quite prolific. Are they alive and reproducing, you bet. But happy and healthy? I'm not so sure on that one. In most cases that's impossible to measure on a relative scale with such upmost certainty. I should note that this is more in response to generic species commonly found (such as RCS), as naturally one would get more specific indicators with sensitive creatures such as CRS and discus. Sorry, I know that's not quite the topic on hand but just wanted to mention that perspective.

So how do you know your fish are happy and healthy with frequent water changes? If they act exactly the same both ways how do you know they arent happy and healthy? Mollies are livebearers which would breed in a 5 gallon bucket in your garage. Rcs will not breed unless in good conditions. They may havr eggs but they will abandon them.

 

[Rare]

A bit off the topic but within. The municipal water treatment for each city is different for each of us. So by time they leave & hit our homes & now sit in our copper lines & who knows what else thing they are collected on the way. We hit what many post on the quality of life for our fish. If this is the case should we be doing RO/DI water & added back the traces of mineral we took out for the BEST quality of water for our fish? I'm just giving this a different spin within the same lines. This is a very good discussion on the topic by the way.

As for me I good nuts on water change and do 80% on the 130 cichlid tank. That water doesnt go to waste as it also feeds the lawn & other plants
& 5g/10g on the 29g saltwater tank.

 

[Cactuspixie]

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.

Lol. Aqua_chem is probably the only chemist here! You are probably going to have to research some academic journals to get the info you require. I have read some and after a few lines all I get from it is 'blah blah blah'. I wish my brain wasn't pudding and could still grasp academic literature, but alas, I need to have it interpreted for me.
In the absence of a clear understanding of the concepts, my safest course is to change out water regularly.

 

[aqua_chem]

I'm going do some reading tonight to see what I can find. The thing is that in a confined aquarium, compounds build up to levels that are many times that which would be found naturally, so their might not be much literature about aquaculture specifically as it's a pretty novel circumstance in the grand scheme of things.

 

[azmodan]

So how do you know your fish are happy and healthy with frequent water changes? If they act exactly the same both ways how do you know they arent happy and healthy? Mollies are livebearers which would breed in a 5 gallon bucket in your garage. Rcs will not breed unless in good conditions. They may havr eggs but they will abandon them.

Sorry I think we're getting a bit off topic here. That was my point, that you can't quite know either way in most cases and because of that it becomes difficult to measure what are acceptable levels for toxins in a closed system like a fish tank. Anyway, I'm just trying not to steer it down that path.

 

[GodFan]

Sorry I think we're getting a bit off topic here. That was my point, that you can't quite know either way in most cases and because of that it becomes difficult to measure what are acceptable levels for toxins in a closed system like a fish tank. Anyway, I'm just trying not to steer it down that path.

I think we are straying off topic but also not. Whether or not we can determine the health of our fish helps us understand the need for water changes.

 

[Delapool]

For myself it has confirmed water changes. My reasoning is that if I'm seeing drift in the macro specs that I can measure when I don't do sufficient water changes (eg kh) then there must be changes in the micro specs. Thoughts?

 

[GodFan]

For myself it has confirmed water changes. My reasoning is that if I'm seeing drift in the macro specs that I can measure when I don't do sufficient water changes (eg kh) then there must be changes in the micro specs. Thoughts?

Im not sure that doing a water change once every month or 2 will allow you to ses a change in macros.

 

[Wy Renegade]

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...

No, nitrate is taken up by plants and converted into amino acids. When those plants die, the amino acids are converted into ammonia and then nitrites and finally nitrates. The point was that without removing plants/algae from the system, you haven't removed them from the system, you've only change the form of nitrogen present.

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.

Quite correct, I did indeed misunderstand your last post. You are correct, they don't store nitrates, they store nitrogen in the form of amino acids, which are converted into proteins, which results in growth.

 

[Delapool]

Im not sure that doing a water change once every month or 2 will allow you to ses a change in macros.

-I'm not sure either as I don't do that.-

 

[aqua_chem]

Randy, my only problem with your logic (if I understand it correctly) is that it leads to some pretty odd conclusions. If removal of ammonia can only be done by removing plants, then keeping plants is essentially keeping a reservoir of ammonia in your tank, ready to foul up at a moments notice. As such, having plants is, by itself, a liability.


With respect to inorganic nitrogenous waste, I'm more than content to call plant mass the successful removal of nitrogen from the system as it's essentially sequestered from interacting with (and therefore harming) much of anything.

 

[aqua_chem]

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.

This got buried a few pages back, but I think it's an excellent point as well. If you're having to constantly top off the aquarium but aren't removing water, TDS will accumulate. An 'oh crap' moment occurs several month later, and you do an emergency 50-70% water change, which results in a rapid, stressful drop in TDS/osmotic pressure in the tank, which could shock a fish. This seems like an incredibly likely scenario to me that you might not ever think about otherwise.

 

[Billbug68]

No, nitrate is taken up by plants and converted into amino acids. When those plants die, the amino acids are converted into ammonia and then nitrites and finally nitrates. The point was that without removing plants/algae from the system, you haven't removed them from the system, you've only change the form of nitrogen present.

Okay, good. This is what I was hoping you meant. My only problem with what you're saying is you're assuming plants will die and be left to rot. Which, I don't believe many people just let happen. Proper care, trimming problem leaves, thriving growth, etc., will remove nitrate, which is why I'm saying to leave nitrate out of the discussion.

Still, nobody has provided exactly WHAT will build up in a planted tank that requires frequent water changes. TDS, maybe, but if you're topping of with RO or distilled like a lot of planted tank keepers doing weekly water changes do, TDS shouldn't build up as much.

And what in the system contributes to TDS? Iron and things alike? Won't plants uptake some of these dissolved solids as well? Don't fish use some of this stuff for say, gill health, slime coat, etc...?

 

[GodFan]

This got buried a few pages back, but I think it's an excellent point as well. If you're having to constantly top off the aquarium but aren't removing water, TDS will accumulate. An 'oh crap' moment occurs several month later, and you do an emergency 50-70% water change, which results in a rapid, stressful drop in TDS/osmotic pressure in the tank, which could shock a fish. This seems like an incredibly likely scenario to me that you might not ever think about otherwise.

Aquachem I cant quote your other post as I am on the app but I want to respond to both. I had never heard of he amino acid thing before. It is interesting and makes sense. After all those nitrates dont just disappear. This seems to mean that as long as the plant is alive the nitrates are stored. Then if the plant dies and the aquarist doesnt remove it hen the nitrates can be released back in correct?
Honestly I have had a bunch of these conversations about water changes. I have learned alot. Everytime I walk away remembering why water changes are absolutely necessary. However I also walk away realizing that the frequency of the water change will vary based on each situation. In many cases once a month would be adaquete. In some once a week. In some twice a week.
I really believe that once a month water changes in the right setup would be plenty to keep TDS down enough in case of an "oh crap" moment. Obviously jot in all setups but imo alot of setups would be fine like this.

 

[aqua_chem]

Then if the plant dies and the aquarist doesnt remove it then the nitrates can be released back in correct?

Yes. Plants put ammonia/nitrite/nitrate into amino acids, among other molecules, which are the 'building blocks' that plants use to make just about everything. When they die, bacteria break down said building blocks and re-release ammonia, which goes back into the water column. That being said, a live plant won't be releasing ammonia pretty much ever.

I really believe that once a month water changes in the right setup would be plenty to keep TDS down enough in case of an "oh crap" moment. Obviously jot in all setups but imo alot of setups would be fine like this.

I have to top off water way to much here to be comfortable with that, but as you've pointed out, each case should be considered individually.

 

[jetajockey]

I don't know if its been mentioned but one reason for frequent pwc in fish tanks is supposed hormone buildup contributing to stunting or other problems.

Another reason for pwc in plant tanks is salt or particular nutrient buildup, the plants do not utilize everything we dump in.

The strict weekly wc thing is just a preference to many, its not the be-all.

 

[aqua_chem]

Still, nobody has provided exactly WHAT will build up in a planted tank that requires frequent water changes. TDS, maybe, but if you're topping of with RO or distilled like a lot of planted tank keepers doing weekly water changes do, TDS shouldn't build up as much.

In the reading I've been doing, it doesn't seem like anyone knows exactly what the dissolved organics consist of. It's likely an immense number of different compounds ranging from metabolites to protein fragments to who knows what. That being said, high levels of organics are well known to cause problems in aquaculture (eg, fish farms), such that it is recommended that these system replace 5-10% per day, roughly in line with EI's standard of 50% per week that's considered extreme. They take it very seriously. I also read an article that showed that higher levels of organics made trace metals more toxic to fish because the way they interacted made them more bioavailable (this study was done on rainbow trout, which are by many standards a bit more sensitive than some species).

And what in the system contributes to TDS? Iron and things alike? Won't plants uptake some of these dissolved solids as well? Don't fish use some of this stuff for say, gill health, slime coat, etc...?

For our purposes, ions contribute most to TDS, most importantly sodium and calcium. Not changing water necessarily means adding water, which means you're introducing both water and ions to replace just water. So if you lose 5% of your volume per day (totally made up number mind you), by the end of the week, your tank water will have 45% more TDS than your tap.

As far as iron or other nutrients being utilized, yes, plants will take it up, and I don't think it will contribute much to TDS compared to the other factors.

 

[Wy Renegade]

Randy, my only problem with your logic (if I understand it correctly) is that it leads to some pretty odd conclusions. If removal of ammonia can only be done by removing plants, then keeping plants is essentially keeping a reservoir of ammonia in your tank, ready to foul up at a moments notice. As such, having plants is, by itself, a liability.


With respect to inorganic nitrogenous waste, I'm more than content to call plant mass the successful removal of nitrogen from the system as it's essentially sequestered from interacting with (and therefore harming) much of anything.

If you follow the saltwater side, the effective removal of nitrogen from the system is accomplished by the trimming removal of the algae grown in the refugium/sump. Algae is far more of a liability than plants per say, because algae can die in mass quantities in a very short time. Some types of algae will die in mass quantities overnight as a result of reproducing.

The simple fact of the matter is that if you are keeping any living organism in your tank, you are keeping a reservoir of nitrogen in the tank. What happens to a tank when a fish dies, and is allowed to decompose in the tank? We see an ammonia spike. The same would be true if a large quantity of plants was allowed to die and decompose within the tank.

The best method for preventing this reservior from being an issue is to monitor your tank on a regular basis ~ as Billbug pointed out, most people don't allow a large dead plant mass to simply sit in the tank and decompose. But what happens when you are away on vacation or you simply get busy and don't pay enough attention to the tank?

While I agree with the observation that the plant mass has sequestered the nitrogen from interacting with (and therefore harming) much of anything, it has in fact not been removed from the system. The same amount of nitrogen is present in the system, although in a different form. As plants grow and you remove those plants to sell or trade, then you have effectively removed the nitrogen from the system.

On the saltwater side, aquarist regular harvest and trim their algae in order to remove nitrogen. Of course on the saltwater side, some also use deep sandbeds and most use LR and the anaerobic bacteria they contain to convert nitrates into harmless nitrogen gas and thereby gas off nitrogen.

Some of my hobby research over the past couple of years has been into the existence of similar anaerobic bacteria within the freshwater environment. If they can be used successfully on the saltwater side of things, they should also be able to be used on the freshwater ~ but that is a whole other discussion in and of itself.