# Fertilizers and effect on TDS and fish



## happi (Dec 18, 2009)

the_deeb said:


> I finally have some fertilizers on their way so I can start to fertilize my paludarium. I ordered the Macro Micro Nutrient Mix from aquariumfertilizer, which contains Potassium Nitrate, Potassium Sulfate, Magnesium Sulfate and Plantex CSM+B. Based on advice that I received in another thread, I'm planning on following a 1/2 dose EI dosing regime.
> 
> One concern that's recently come to mind is how significantly the addition of fertilizers will alter my TDS levels. I've come across some reports that suggest that clown loaches are sensitive to fluctuations in TDS, and I've observed some possible symptoms of this when I've done large water changes. This has me a little nervous.
> 
> Has anyone ever measured fluctuations in TDS levels during a standard EI dosing regime? Has anyone experienced negative effects on fish as a result of fertilizing? Anyone with personal experience with fertilizing a loach tank?


nothing else will cause the TDS to raise beside magnesium and calcium, i personally do not add them due to my water being hard. if you have to dose them, dose them once a week when changing the water.


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## snausage (Mar 8, 2010)

happi said:


> nothing else will cause the TDS to raise beside magnesium and calcium, i personally do not add them due to my water being hard. if you have to dose them, dose them once a week when changing the water.


That is incorrect. All fertilizers will significantly raise TDS, as TDS is essentially a measure of everything dissolved in your H2O that isn't H2O. For example, fish waste will increase TDS as well as all water soluble formulations of N, P, K, etc.

It generally isn't such a big problem and most likely won't lead to any deaths or ill health in healthy specimens. Just make sure you maintain a regular water change schedule that equals approx 50% of the tank.


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## Darkblade48 (Jan 4, 2008)

I used to dose EI in a planted aquarium with Clown Loaches, with no problems.


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## plantbrain (Dec 15, 2003)

I keep a large group of dwarf loaches, 










TDS does not matter, O2 and CO2 do and far far far far far far more important.
Did I say "far more" enough?

I've never met anyone that's ever killed or other wised harmed any fish using EI
About weekly we see someone who gassed their fish by either too little flow saving the CO2, or impatient with CO2 or a combo of both.

Those are the facts after 15 years.

I dumped the entire liquid fert for 2 weeks into a tank once and the NO3 was about 200 ppm for 2 weeks, then the K+ was about 290ppm, PO4 was about 65ppm etc. TDS was likely 6-7X what is should have been, no ill effects on any fish, I did lose some Amano shrimp, but it is hard to say what did them in.

Still, even with gross mistakes, there's no risk any one has demonstrated to date.

Folks should worry more about light(adding too much) and then careful metered control of CO2.


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## happi (Dec 18, 2009)

snausage said:


> That is incorrect. All fertilizers will significantly raise TDS, as TDS is essentially a measure of everything dissolved in your H2O that isn't H2O. For example, fish waste will increase TDS as well as all water soluble formulations of N, P, K, etc.
> 
> It generally isn't such a big problem and most likely won't lead to any deaths or ill health in healthy specimens. Just make sure you maintain a regular water change schedule that equals approx 50% of the tank.


i think you are right, i was going based on what is the main cause of TDS. yes i agree with you and my dosing also make the water hardness increase overtime.


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## snausage (Mar 8, 2010)

happi said:


> i think you are right, i was going based on what is the main cause of TDS. yes i agree with you and my dosing also make the water hardness increase overtime.


A lot of people confuse TDS with cumulative hardness measured in ppm.


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## the_deeb (Mar 19, 2009)

Thanks for the responses, they're very reassuring.

Tom - I'm wondering if the TDS issue I mentioned may be specific to clown loaches (BTW, beautiful sidthimunkis - I love those little guys). I don't know if it's even really that much of a problem. My loaches recently developed some black freckles after a period when I was doing daily 50% water changes. I came across a thread on the loaches online forum that where one person provided some pretty good evidence that this may be caused by fluctuations in TDS. There's no real indication that they cause any harm to the fish so they may just be cosmetic blemishes, but I just wanted to make sure that dosing ferts wouldn't make them any worse.

I don't use CO2 in this setup and the water is certainly very well oxygenated due to my drip wall.


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## boringname (Nov 11, 2010)

happi said:


> nothing else will cause the TDS to raise beside magnesium and calcium, i personally do not add them due to my water being hard. if you have to dose them, dose them once a week when changing the water.



Do you mean only magnesium and calcium will change the reading on a TDS meter? I think TDS meters are really electrical conductivity meters and only ionized particles will change the reading.


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## snausage (Mar 8, 2010)

boringname said:


> Do you mean only magnesium and calcium will change the reading on a TDS meter? I think TDS meters are really electrical conductivity meters and only ionized particles will change the reading.


No, all ferts will cause higher readings on the TDS meter, as they all increase TDS


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## plantbrain (Dec 15, 2003)

the_deeb said:


> Thanks for the responses, they're very reassuring.
> 
> Tom - I'm wondering if the TDS issue I mentioned may be specific to clown loaches (BTW, beautiful sidthimunkis - I love those little guys). I don't know if it's even really that much of a problem. My loaches recently developed some black freckles after a period when I was doing daily 50% water changes. I came across a thread on the loaches online forum that where one person provided some pretty good evidence that this may be caused by fluctuations in TDS. There's no real indication that they cause any harm to the fish so they may just be cosmetic blemishes, but I just wanted to make sure that dosing ferts wouldn't make them any worse.
> 
> I don't use CO2 in this setup and the water is certainly very well oxygenated due to my drip wall.


Clowns are tough as nails and get huge in every tank I've owned for the last 35 years.

Never an issue.


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## boringname (Nov 11, 2010)

snausage said:


> No, all ferts will cause higher readings on the TDS meter, as they all increase TDS


TDS meters measure electrical conductivity and only ionized particles will increase that.


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## Hoppy (Dec 24, 2005)

boringname said:


> TDS meters measure electrical conductivity and only ionized particles will increase that.


But, every inorganic chemical that dissolves in water adds ions to the water, right? So, all of the fertilizers we use, being soluble in water, add ions. When a salt dissolves, it becomes ions in the water. Can one of you chemist types confirm that?


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## snausage (Mar 8, 2010)

boringname said:


> TDS meters measure electrical conductivity and only ionized particles will increase that.


Take a TDS reading, dose your macros, take another reading. I guarantee your TDS will rise significantly. Hardness is only one component of TDS. You can very easily have an extremely high TDS reading and little or no gH or kH.



Hoppy said:


> But, every inorganic chemical that dissolves in water adds ions to the water, right? So, all of the fertilizers we use, being soluble in water, add ions. When a salt dissolves, it becomes ions in the water. Can one of you chemist types confirm that?


I'm not a chemist, but you're definitely correct.


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## Darkblade48 (Jan 4, 2008)

Hoppy said:


> But, every inorganic chemical that dissolves in water adds ions to the water, right? So, all of the fertilizers we use, being soluble in water, add ions. When a salt dissolves, it becomes ions in the water. Can one of you chemist types confirm that?


You are correct.

Organics can also contribute to TDS.


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