Importance of TDS

[Caliban07]

It is more than likely (actually probably) that the "pH shock" myth is, in fact, caused by large differences in TDS. The exception would be a situation where there is ammonia in the water and the pH is low (below 7) and a sudden increase in pH causes the ammonia to become toxic. This happens with fist that are trans shipped in regular plastic bags. The high level of CO2 causes the pH to drop, and when the bag is opened, the CO2 gasses off quickly and the ammonium becomes ammonia which is toxic. In this situation, removing the fish quickly, even to water of different TDS, is better than trying to acclimate.
I was first introduced to the importance of TDS by Joe Gargas, many years ago, He had just become head of R & D for Wardley and was up here for a speaking engagement. Some of you may remember him as a regular contributor to FAMA magazine. We had quite a chat in the local Big Al's, about different things he came across as a consultant and the importance of TDS.

Thanks Bill. What did he have to say?


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[Delapool]

It is more than likely (actually probably) that the "pH shock" myth is, in fact, caused by large differences in TDS. The exception would be a situation where there is ammonia in the water and the pH is low (below 7) and a sudden increase in pH causes the ammonia to become toxic. This happens with fist that are trans shipped in regular plastic bags. The high level of CO2 causes the pH to drop, and when the bag is opened, the CO2 gasses off quickly and the ammonium becomes ammonia which is toxic. In this situation, removing the fish quickly, even to water of different TDS, is better than trying to acclimate.
I was first introduced to the importance of TDS by Joe Gargas, many years ago, He had just become head of R & D for Wardley and was up here for a speaking engagement. Some of you may remember him as a regular contributor to FAMA magazine. We had quite a chat in the local Big Al's, about different things he came across as a consultant and the importance of TDS.

I kind of have to disagree with that on ph shock myth. I've seen enough threads now where a ph decrease has resulted in unhealthy fish. Is the ph tracking a change in TDS which I assume includes kh? Well could be and that I would agree with. Either way imo measuring ph is still important.

I know fish will deal with rapidly changing ph just as they will also deal with say salt dips.

Page 9 of this report suggested ionic shock was important but still reading.


https://www.adfg.state.ak.us/static/home/library/pdfs/habitat/01_06.pdf

Edit - by ph shock are you referring to shifts in ph from say co2 dosing where I would assume kh does not shift that much?

 

[Caliban07]

I kind of have to disagree with that on ph shock myth. I've seen enough threads now where a ph decrease has resulted in unhealthy fish. Is the ph tracking a change in TDS which I assume includes kh? Well could be and that I would agree with. Either way imo measuring ph is still important.

I know fish will deal with rapidly changing ph just as they will also deal with say salt dips.

Page 9 of this report suggested ionic shock was important but still reading.


https://www.adfg.state.ak.us/static/home/library/pdfs/habitat/01_06.pdf

Edit - by ph shock are you referring to shifts in ph from say co2 dosing where I would assume kh does not shift that much?

I think what BillD was getting at is that many moons ago in this hobby (sorry BillD) perhaps at a time when there was less understanding. Hobbyists would claim that when a fish died after a water change it was the ph that had caused the deaths so the term 'ph shock' came about. Since then I believe what BillD was trying to say was that this ph shock and resultant fish deaths has been found out to actually be related to fluctuations in TDS.

I'm sure he understands that altering ph levels can be fatal fish. He was just dispelling that 'ph shock' myth but ph changes damaging fish is certainly not a myth.


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[Masha]

Is TDS related to "old tank syndrome" ?

 

[Delapool]

I think what BillD was getting at is that many moons ago in this hobby (sorry BillD) perhaps at a time when there was less understanding. Hobbyists would claim that when a fish died after a water change it was the ph that had caused the deaths so the term 'ph shock' came about. Since then I believe what BillD was trying to say was that this ph shock and resultant fish deaths has been found out to actually be related to fluctuations in TDS.

I'm sure he understands that altering ph levels can be fatal fish. He was just dispelling that 'ph shock' myth but ph changes damaging fish is certainly not a myth.


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Ah, got it. Makes sense.

 

[Delapool]

Is TDS related to "old tank syndrome" ?

Thinking about it I would of had tanks go months and then a major pwc.

Ph and kh would probably have dived,
nitrates up (although plants grew well),
gh would of increased (although maybe not much as not much evaporation),
plants would of changed water chemistry, and (wait for it)
I would of carefully cleaned out the filter wool and carbon (only stuff in filter).


It's a wonder any fish did survive. If I had to guess, I would say I had a 20% death rate after a pwc change like that. Enough to notice but not enough to buy a heap of new fish from memory. Not sure how much TDS would of changed.

 

[Caliban07]

Thinking about it I would of had tanks go months and then a major pwc.

Ph and kh would probably have dived,
nitrates up (although plants grew well),
gh would of increased (although maybe not much as not much evaporation),
plants would of changed water chemistry, and (wait for it)
I would of carefully cleaned out the filter wool and carbon (only stuff in filter).


It's a wonder any fish did survive. If I had to guess, I would say I had a 20% death rate after a pwc change like that. Enough to notice but not enough to buy a heap of new fish from memory. Not sure how much TDS would of changed.

In most cases there may be no repercussions. There are probably some people who have read this thinking it's an over reaction and nothing to worry about. I have certainly spoken to people who think TDS is negligible.

My point is, although fish may appear to be acting normally, they are still having to adapt to the new water chemistry post water change. In fact scrub that. They are always adapting to changing water chemistry. Too much of a change can overwork the osmoregulatory system and have a negative affect on the fish. Are there times when the fish don't bat an eyelid? You bet. Are there going to be times when the fish doesn't handle this change well? I'll say.


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[Delapool]

In most cases there may be no repercussions. There are probably some people who have read this thinking it's an over reaction and nothing to worry about. I have certainly spoken to people who think TDS is negligible.

My point is, although fish may appear to be acting normally, they are still having to adapt to the new water chemistry post water change. In fact scrub that. They are always adapting to changing water chemistry. Too much of a change can overwork the osmoregulatory system and have a negative affect on the fish. Are there times when the fish don't bat an eyelid? You bet. Are there going to be times when the fish doesn't handle this change well? I'll say.


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Well, fish were probably tougher then. They had to be to survive the push bike ride home.

I should of added that fish loses were a constant trickle though. This sort of information that you have kindly compiled makes a big difference imo.

 

[Caliban07]

Is TDS related to "old tank syndrome" ?

I think so personally. I've not looked in to what the majority of hobbyists classify as old tank syndrome but a tank that has been up and running for many years will have a much greater TDS concentration than when it was first setup. It's obvious that this incline is slow and so the fish can adapt with little effort but the probability of major fluctuations has also increased which makes water changes quite critical. I find that this in itself can be considered a 'syndrome' of some sort.

It doesn't mean that the tank is necessarily dirty but that the concentrations of unwanted dissolved solids has risen although I do believe that the traditional concept of old tank syndrome is a tank that has not received 'enough' water changes over a long period of time which is directly related to an increase in TDS.


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[Masha]

"I do believe that the traditional concept of old tank syndrome is a tank that has not received 'enough' water changes over a long period of time which is directly related to an increase in TDS. "

That makes sense. If you do regular water changes, I can see that TDS would go up, but surely not past a certain point.

 

[Mebbid]

With regular water changes, the tds will creep up over time, however it should only creep up to a certain point. With a little math that I really dont feel like doing now its fairly easy to figure out. However, tds is never stable in the source.

Fish in the wild also see absolutely massive seasonal shifts in tds. My local river is a great example of this. In the spring the water level at least doubles if not more. The amazon does the same thing. Fish have no issues adapting to these irregular and rare changes.

 

[Andy Sager]

With regular water changes, the tds will creep up over time, however it should only creep up to a certain point. With a little math that I really dont feel like doing now its fairly easy to figure out. However, tds is never stable in the source.

Fish in the wild also see absolutely massive seasonal shifts in tds. My local river is a great example of this. In the spring the water level at least doubles if not more. The amazon does the same thing. Fish have no issues adapting to these irregular and rare changes.

I'm not sure you can equate what the amazonian fish go through with the seasonal rains to our tank environments. You see, the Amazon river system has primarily soft acidic water year round. Add to that all the rain which is also probably soft and acidic, the fish are not really going through that much change in water quality. Yes there is some change but not as drastic as you may think. I know this from a former employer who was Brazilian and went back to the Amazon on yearly fish explorations. He told me that in some places where they were finding Discus, the water is so acidic that no insects can survive in it. It even burned his skin a little because it was so acidic. So the changes in water quality in the wild may not be as large even tho the amount of water being changed is large.

Just some FYI

 

[Mebbid]

I am curious about how nutrient sinks such as plants an anaerobic bacteria that consume nitrate manage tds though.

 

[Caliban07]

I am curious about how nutrient sinks such as plants an anaerobic bacteria that consume nitrate manage tds though.

It would be interesting to see. It another case of individuality though. What one person does with their tanks can be completely different to another persons tank. Tap water would have to be taken in to consideration too as well as the type of plant, lighting, ph. The variables are endless. You could use a TDS meter just to see how much TDS rises within a week post water change. Even then we don't know how much of rise is enough to effect our fish.

What I have learned from my research is that large sudden fluctuations in water chemistry can oppress the osmoregulatory system. It forces the fish to deal with an unexpected change and cause undue stress. Fish in the wild where their environment is subjected to rash alterations will have undertaken an evolutionary response and so would be much better equipped to deal with such change. It makes wild caught fish all the more fragile when being added to different waters. I'm not saying that they don't have the physiological functions to be able to deal with the change. I'm just saying that don't be surprised if they don't handle it very well.


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[Masha]

Little off topic here...I've noticed that people often use "fish in the wild" as the gold standard for how to keep fish. Which makes sense, up to a point. But how much do we know about the health, life-span, breeding capacity etc of wild fish in comparison captive bred fish?

I know, for example, that some captive wild animals in zoos live much longer, healthier lives than their wild equivalents. Without predators or the stress of finding food, mates, etc ?

I understand that what we are after is creating an environment that is as close as possible to the one that fish are adapted to, that's just common sense. But maybe "in the wild" isn't always a useful comparison, as things are pretty hairy for fish in the wild, and removing some of those stresses might actually be to their benefit?

Sorry for the off topic post, just something that occurred to me.

 

[threnjen]

Well this is months old but it's such a great article! And I want to bump it, so there!

A TDS meter is really cheap and is a staple in my testing box. I totally believe that TDS is much more important than pH to acclimation.

 

[Brookster123]

Too bad threnjen isn't around anymore, this thread would be on page 5 already; )

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Well this is months old but it's such a great article! And I want to bump it, so there!

A TDS meter is really cheap and is a staple in my testing box. I totally believe that TDS is much more important than pH to acclimation.

Caliban will be ohh soo happy!

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[threnjen]

Haha I saw that on page 1 and felt sooooo guilty

Caliban bugs me on FB to tempt me to come around and hang out. Maybe this time it's actually gonna work! I was trying to be all sneaky asking about my fry

 

[sinibotia]

I've been using TDS as a proxy for hardness (GH) for my discus research project. Got a cheap electronic meter that I use to check the reserve bins of water before I add them.

 

[threnjen]

I've been using TDS as a proxy for hardness (GH) for my discus research project. Got a cheap electronic meter that I use to check the reserve bins of water before I add them.

That makes perfect sense to me.

TDS is such an underappreciated but important concept in the hobby, imo. It tells us so much more than "general hardness" ever can.