# TDS and its use in Planted Tanks



## Mariostg

My 4 tanks have a TDS ranging from 350 to over 1100ppm. TDS is what I measure most often although I measure it maybe only once a month. In my case I don't do water change and just add potassium and iron.

I don't know how high quality your device is but depending how deep you place the probes will affect the reading. But even without adding anything in the tank, plants decay, they also release chemicals in the water and also do the fishes, even in small quantities. That will affect the reading. Substrate will also release stuff and so will wood if you have any.


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## Maryland Guppy

Shells, limestone type rocks or aggregate, concrete hardscapes, and any calcium
based anything will all slowly dissolve adding to the overall TDS in the aquarium.
Any of these present in your tank?

Granites and quartz typically will not alter the TDS.

Plants: I have found that some plants growth has came to a halt with too high of a TDS.
In my case water sprite would not grow and became stunted over 350 TDS.
Enough water changes to stay around 225-250 and quick growth returned.
This was the only variable I changed at the time.

I use TDS as an indicator for water changes.
Over 300 and I plan for some quantity of water to change.
For me this is 4 - 8 gallons a week in a 40 gallon with a large concrete hardscape.


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## bcarl_10gal

Thanks for the input, Yes I understand plant matter, fish, hardscape all affect the TDS but 15ppm over 8 hours seems like A LOT especially for a low fish load. The measurements were taken at the same depth in the tank as well. I do have Seiryu stones but they are probably only a pound in a 26 gallon tank. Shouldn't impact the water too much.


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## keymastr

Maybe you are using too much GH booster. I use Equilibrium and strictly RO water and found that the directions for 6dgh water gave me a tds reading of over 350. I have since cut that dose in half.


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## bcarl_10gal

But that does not explain the 15 ppm increase over 8 hours


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## Mariostg

Maryland Guppy said:


> Shells, limestone type rocks or aggregate, concrete hardscapes, and any calcium
> based anything will all slowly dissolve adding to the overall TDS in the aquarium.
> Any of these present in your tank?
> 
> Granites and quartz typically will not alter the TDS.
> 
> Plants: I have found that some plants growth has came to a halt with too high of a TDS.
> In my case water sprite would not grow and became stunted over 350 TDS.
> Enough water changes to stay around 225-250 and quick growth returned.
> This was the only variable I changed at the time.
> 
> I use TDS as an indicator for water changes.
> Over 300 and I plan for some quantity of water to change.
> For me this is 4 - 8 gallons a week in a 40 gallon with a large concrete hardscape.


Interesting, I have water sprite, water wisteria, guppy grass, Egeria densa in that 10 gal tanks that has 1100ppm TDS and must trim them all once in a while. Oh, there is also some parrot feather and java moss.

Bump:


bcarl_10gal said:


> But that does not explain the 15 ppm increase over 8 hours


How about when you make the measurement at the same time of the day. Things like pH may change throughout the day.


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## Maryland Guppy

Mariostg said:


> Interesting, I have water sprite, water wisteria, guppy grass, Egeria densa in that 10 gal tanks that has 1100ppm TDS and must trim them all once in a while. Oh, there is also some parrot feather and java moss.


I only noticed this with water sprite. No other plants.
I can't explain all this mess, just what happened with mine.
Maybe since it didn't grow an inch a day I thought something was wrong?

It's tough here, we all have so many different variables.
Due to locations our water sources differ considerably.
If it's growing we are doing something right.


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## Mariostg

Maryland Guppy said:


> I only noticed this with water sprite. No other plants.
> I can't explain all this mess, just what happened with mine.
> Maybe since it didn't grow an inch a day I thought something was wrong?
> 
> It's tough here, we all have so many different variables.
> Due to locations our water sources differ considerably.
> If it's growing we are doing something right.


Agreed. Well glad it doesn't grow an inch a day. Mind you that's almost what the guppy grass does.


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## bcarl_10gal

On the plant debate, a TDS out of the faucet at 800 and in the tank with 1100 would be far different from water out of the tap with a TDS of 300 and a tank TDS of 1100. The chemical makeup of the water would be quite different. 

The only fluctuation in the pH over the course of the day is impacted by Co2, so from my understanding it shouldn't impact it. I checked the TDS around 11am and it was still at 385. We will see what it is at 8pm tonight.


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## Mariostg

bcarl_10gal said:


> On the plant debate, a TDS out of the faucet at 800 and in the tank with 1100 would be far different from water out of the tap with a TDS of 300 and a tank TDS of 1100. The chemical makeup of the water would be quite different.
> 
> The only fluctuation in the pH over the course of the day is impacted by Co2, so from my understanding it shouldn't impact it. I checked the TDS around 11am and it was still at 385. We will see what it is at 8pm tonight.


Not sure if you are referring to anyone in particular here, but my TDS out of the faucet is around 60ppm. My tanks are about a year old. so the TDS just built up overtime.


All I was saying is that water parameters may fluctuate throught the day hence it's best to do it at the same time.


You should elaborate more on the conditions in your tank. You mentionned about GH booster, but what do you dose for ferts? Also, which plants are specifically affected? Not sure you mentionned the substrate used.


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## bcarl_10gal

No, I wasn't referring to either of you. But yeah, TDS does build up over time. I am testing the TDS at the same time as well, once at 8am then again at 8pm. 

As for the tank it has ecocomplete, dosed EI, injected CO2 and high light. Specific plants are s.repens, AR mini and ludwigia sp. red has some curled leaves, macandra. Plants that are fine include, purple cabomba, pogo, bylxa


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## bcarl_10gal

So I didn't see the 15ppm jump in TDS overnight which is good i guess. However when I added my fert solutions this morning I expected it to increase by 22ppm by adding up all the nutrients on YANC. The TDS in the tank went up 35ppm. The solutions are mixed in 0 TDS water from my RO/DI. Is there something I am not considering for a rise of 15ppm?


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## Audionut

Did you add up all the stuff that comes along for the ride? SO4 from MgSO4 for instance.


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## keymastr

TDS stands for Total Dissolved Solids which I am sure you know. Everything you put into your fish tank is constantly dissolving a little at a time. Plants, rocks, wood, ferts, dechlorinator, food etc. Especially food. Fish process it and what they produce is dissolved solids as well. 

TDS meters are mostly useful for telling you when your water needs changed and it can be a general guide as to the hardness of your water supply but once that water has entered the tank the amount of TDS has little to do with water hardness since it is impossible to say what dissolved solids you are measuring. Is it a mineral or is it nitrate?

And an increase of 5% overnight does not seem so alarming.


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## Jaxfisher

And water evaporation will also increase your TDS...


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## bcarl_10gal

So after tracking it for a few weeks, it seems like while dosing EI the TDS creeps up by about 100ppm per week. I found a thread that Tom Barr said his TDS moves by about 100ppm or so between water changes. Since I use a blend of RO water my initial tank should be about 150ppm and should rise to only 250ppm before needing a water change. My tank was at 550ppm last week. I have been slowly bringing it down with frequent water changes. I am curious to see how this affects plant growth.


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## PortalMasterRy

bcarl_10gal said:


> So after tracking it for a few weeks, it seems like while dosing EI the TDS creeps up by about 100ppm per week. I found a thread that Tom Barr said his TDS moves by about 100ppm or so between water changes. Since I use a blend of RO water my initial tank should be about 150ppm and should rise to only 250ppm before needing a water change. My tank was at 550ppm last week. I have been slowly bringing it down with frequent water changes. I am curious to see how this affects plant growth.


Unless your plants are showing signs that your nutrients are in excess then I would not bother cutting it back. The problem with cutting back the TDS with water changes is you might be cutting back on some nutrients that the plants need to grow. Unless you are checking water parameters then it would be impossible to tell if the nitrate or phosphate or even GH and KH are at optimal levels. Just do your weekly water changes then you should be fine. 

Remember EI is about providing non-limiting amount of nutrients. A little excess is actually fine because you do weekly changes means the nutrients in the water will level out after your consistent weekly water changes which is key in doing EI.


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## dzega

i use TDS to determine when WC is needed. tank evaporates distilled water wich raises TDS, at certain point i change the water to bring it back down


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## bcarl_10gal

I have been having issues with a few plants for the past few months that I still have not figured out (this is discussed in other threads). I monitor, Nitrate, Phosphate, KH, GH, etc. What I found interesting that when the TDS was at 550 none of my measurements were crazy high.


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## Mariostg

dzega said:


> i use TDS to determine when WC is needed. tank evaporates distilled water wich raises TDS, at certain point i change the water to bring it back down


Out of curiosity, what is your threshold?


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## Italionstallion888

How's this going?


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## bcarl_10gal

Life has gotten very busy so my TDS monitoring has been spotty at best. Overall id say that the results were inconclusive. I didnt see much difference.


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## SamFrogs

I know this is an old post but, I measured my TDS every other day and is very stable at 160ppm (±5). Is this too little.for my plants?

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