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Lowering tds...

plantnoobdude

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At the moment my tds floats around 100 in my high tech tank, around 65 of it is from my remineraliser. I want to get this lower, the majority of my tds is made up of relatively useless cl and S
because of this I want to get rid of it, I will stop using K2so4 by swapping it out for kno3. and now I want to deal with my remineraliser where the bulk of cl and s comes from.
I was thinking whether or not I could use caco3 and mgco3 and then react the co3 with hcl to get kh less water with lower so4 and cl, but I am wondering whether or not there will be more cl from hcl than originally in cacl? anyone with insights on this topic? cheers,
 

Maf 2500

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Combine your ferts with your remineralistion and make use of calcium nitrate, magnesium nitrate, potassium nitrate etc. No chlorides or sulphates.
 

MichaelJ

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At the moment my tds floats around 100 in my high tech tank, around 65 of it is from my remineraliser. I want to get this lower, the majority of my tds is made up of relatively useless cl and S
because of this I want to get rid of it, I will stop using K2so4 by swapping it out for kno3. and now I want to deal with my remineraliser where the bulk of cl and s comes from.
I was thinking whether or not I could use caco3 and mgco3 and then react the co3 with hcl to get kh less water with lower so4 and cl, but I am wondering whether or not there will be more cl from hcl than originally in cacl? anyone with insights on this topic? cheers,
Hi @plantnoobdude By " 65 of it is from my remineraliser" I assume you mean from CaCl2 or CaSO4, MgSO4 to raise your GH... I've been there. Look into Ca Gluconate and Mg Gluconate. You might not want to go all-in on the Gluconate, but you can easily use quite a bit of Ca and Mg Gluconate to shave off a lot of that excess SO4 or Cl (you do need "some" S and Cl though). I've been doing that for a while now with no negative side effects so far.

Just as an example for Ca:

If you target 20 ppm of Ca with CaCl2 you get 35 ppm of C a total of 55 ppm.
If you target 20 ppm of Ca with CaSO4 you get 16 ppm of S a total of 36 ppm. (Note: CaSO4 is less soluble than CaCl2, but its a total non-issue unless you're targeting unrealistic high Ca levels).
If you target 20 ppm of Ca with Ca Gluconate you only get the 20 ppm of Ca with nothing else that will raise TDS... However, you will be getting a lot of Gluconate - which is a glucose derivative (sugar) and organic compound that may possibly trigger bacterial blooms if used in excess - which happened to me in the past because I went overboard.

My recommendation would be to target half of your Ca needs with Ca Gluconate and the rest with CaSO4 (perhaps with a little bit of CaCl2 mixed in if your not not getting any Cl from other sources) - and likewise half your Mg needs with Mg Gluconate and the rest with MgSO4 or even better, depending on your NPK targets, MgNO3. That should shave off a lot of TDS.

Getting the TDS down while making sure you get all the necessary Ca, Mg and NPK takes a bit of juggling. But using @Hanuman / @Zeus. excellent IFC Calculator should get your there without too much trouble.


Cheers,
Michael
 
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plantnoobdude

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Have you used the IFC calculator? You could play around to see which provides more or less.
I am using the Ifc calculator.
If I may, what is the rational to reduce your TDS so low? 65 TDS for remin is already rather on the low side. What are your current remin targets and dosage?
for fun:lol: to get the water with as little "stuff" in it as possible.
18ppm Ca and 6ppm Mg from cacl2h2o and Mgso47h2o is what I use.
Combine your ferts with your remineralistion and make use of calcium nitrate, magnesium nitrate, potassium nitrate etc. No chlorides or sulphates.
I do not want too much No3 in the water as I am using Urea for N.

but you can easily use quite a bit of Ca and Mg Gluconate to shave off a lot of that excess SO4 or Cl (you do need "some" S and Cl though
It does seem good but, the bacterial blooms do not appeal to me as well as the fact that I won't to be able to get that much off of it.

I also cannot seem to find Mg and Ca gluconate in pure forms, most of it seems to be sold as a part of a pill.
 

MichaelJ

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It does seem good but, the bacterial blooms do not appeal to me as well as the fact that I won't to be able to get that much off of it.
Hi @plantnoobdude I hear you. I never really understood what happened in my case when I used a lot of it and I got very cloudy water - was it a bacterial bloom, precipitation of sorts or other interaction? I have no idea. My guess is a bacteria bloom considering the organic matter (sugar) that makes up the Gluconate. When I finally figured out the amounts of Ca and Mg Gluconate that was "safe" in the sense that I no longer got cloudy waters I did get quite a bit of milage out of it though - and was able to shave off 30 ppm or so of my TDS (vs the 100% use of MgSO4 and CaSO4)... whether thats worthwhile obviously depends on what you want to achieve etc. What compounds are you using right now for remineralization? and what Ca and Mg ppms are you targeting?

I have noticed that at least one reputable fertilizer company have started using Gluconate in their remineralizers such as Nilocg Regen GH Booster. How much they are using, and how well its been researched I do not know.

I also cannot seem to find Mg and Ca gluconate in pure forms, most of it seems to be sold as a part of a pill.

I am using this powder-form product for Ca Gluconate. They have a similar product for Mg.

Cheers,
Michael
 
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plantnoobdude

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whether thats worthwhile obviously depends on what you want to achieve etc. What compounds are you using right now for remineralization? and what Ca and Mg ppms are you targeting?
cacl and mgso4. targeting 18ppm Ca and 6ppm Mg.

I was thinking Hcl would work well, but i'm not sure how much cl would be added in the progress...
 

plantnoobdude

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You could go CaSO4 instead of CaCl2 - just that would shave off ~17.5 ppm of TDS for the same amount of Ca.

Cheers,
Michael
yes, true. apparently so4 is a less troublesome anion than cl in our tanks, I dose my remineraliser in liquid form,but i probably wouldnt be able to do that with caso4.
probably will add 0.1ppm or so of cl as well from an alternative source.
but 20ppm or so isn't exactly game changing, still looking for an alternative.... good ca, mg and very little cl and s
 

MichaelJ

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yes, true. apparently so4 is a less troublesome anion than cl in our tanks, I dose my remineraliser in liquid form,but i probably wouldnt be able to do that with caso4.
Hi @plantnoobdude I never experimented much with liquid dosing of remineralizers. I always thought it was too problematic due to solubility and precipitation issues in the mixing bottle. Also, I never had any issues weighting everything out on a microgram scale and just mix it in with my WC water - takes me a minute or two during WC.
probably will add 0.1ppm or so of cl as well from an alternative source.
but 20ppm or so isn't exactly game changing, still looking for an alternative.... good ca, mg and very little cl and s
Well, 65 to 45 ppm is a 30% reduction... thats not bad at all... With your target of 18 ppm of Ca and 6 ppm of Mg your really only left with 21 ppm of "unwanted" TDS and if you would add say 33% of the Ca target as Ca Gluconate you could shave off an additional 5 ppm of the unwanted TDS (you could do the same with Mg Gluconate vs. MgSO4), and bring your total TDS contribution from remineralizers down to 38-40 ppm... I don't see what much else you can do to shave off TDS from the remineralizers except lowering your Ca and Mg targets in general.

Cheers,
Michael
 

plantnoobdude

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Hi @plantnoobdude I never experimented much with liquid dosing of remineralizers. I always thought it was too problematic due to solubility and precipitation issues in the mixing bottle. Also, I never had any issues weighting everything out on a microgram scale and just mix it in with my WC water - takes me a minute or two during WC.

Well, 65 to 45 ppm is a 30% reduction... thats not bad at all... With your target of 18 ppm of Ca and 6 ppm of Mg your really only left with 21 ppm of "unwanted" TDS and if you would add say 33% of the Ca target as Ca Gluconate you could shave off an additional 5 ppm of the unwanted TDS (you could do the same with Mg Gluconate vs. MgSO4), and bring your total TDS contribution from remineralizers down to 38-40 ppm... I don't see what much else you can do to shave off TDS from the remineralizers except lowering your Ca and Mg targets in general.

Cheers,
Michael

liquid dosing I do with two separate solutions, one for ca on for Mg. when mixing cacl and mgso4, I believe it precipitates to form caso4 which is less soluble which is why it often forms white dust at the bottom of my dosing solution previously. solids at the bottom make it very difficult to accurately dose ca/mg at accurate amounts. with separate solutions it is much easier, more accuaret and takes maybe 2-3 seconds longer than one solution.

I will think about ca gluconate and caso4. could work well. seems decent now that you've put the numbers right infront of me! thanks.
 

MichaelJ

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Hi @plantnoobdude How do you dose N/NO3 ? And what do you target? ... I'm using Mg(NO3), so I am getting about 1/3rd of my Mg "budget" from Mg(NO3) (and 100% of my N/NO3). Of course, if your targeting very low levels of N/NO3 its a moot point to use Mg(NO3)...

Cheers,
Michael
 

plantnoobdude

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Hi @plantnoobdude How do you dose N/NO3 ? And what do you target? ... I'm using Mg(NO3), so I am getting about 1/3rd of my Mg "budget" from Mg(NO3) (and 100% of my N/NO3). Of course, if your targeting very low levels of N/NO3 its a moot point to use Mg(NO3)...

Cheers,
Michael
I am dosing Urea solely for N. though i have stopped as i suspect my 2-3 month old aquasoil was leaching more than I thought. in the past month or so I have used anywhere from 1ppm-3ppm N per week (~13ppm No3 equivelant) with the rest of nutrients at 0.39ppm P and 2ppm K
 

MichaelJ

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I am dosing Urea solely for N. though i have stopped as i suspect my 2-3 month old aquasoil was leaching more than I thought. in the past month or so I have used anywhere from 1ppm-3ppm N per week (~13ppm No3 equivelant) with the rest of nutrients at 0.39ppm P and 2ppm K
Hi @plantnoobdude OK, right, there is not much leverage there for piggybacking Ca/Mg on any of those compounds when in such small amounts.

I will think about ca gluconate and caso4. could work well. seems decent now that you've put the numbers right infront of me! thanks.
Yes, I would suggest just doing everything with Ca Gluconate very slowly and monitor the reactions. Start with say 10% and increase in 10% increments at each WC until you reach like 30-40% Ca Gluconate vs. CaSO4.

Cheers,
Michael
 

aquanoobie

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cacl and mgso4. targeting 18ppm Ca and 6ppm Mg.

I was thinking Hcl would work well, but i'm not sure how much cl would be added in the progress..
HCl will not change CaCl2 and MgSO4. HCl will lower your KH by removing HCO3 bicarbonate and release CO2 in the process, and, close your eyes, HCl will increase TDS.

Combine your ferts with your remineralistion and make use of calcium nitrate, magnesium nitrate, potassium nitrate etc. No chlorides or sulphates.
Yes, this is the only way to lower TDS. Also you could consider lowering Ca and Mg. It doesn't have to be this high and lowering it makes significant change to the total TDS readings.
 

Djoko Sauza

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Alternatively you could slowly reduce the amount of Ca and Mg you add until you reach a value you and your livestock are happy with? You'd have to keep an eye on your plants of course but from personal experience we need much less GH than usually advised. My tank is currently at 40tds and plants still growing fine.
 

plantnoobdude

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HCl will not change CaCl2 and MgSO4. HCl will lower your KH by removing HCO3 bicarbonate and release CO2 in the process, and, close your eyes, HCl will increase TDS.


Yes, this is the only way to lower TDS. Also you could consider lowering Ca and Mg. It doesn't have to be this high and lowering it makes significant change to the total TDS readings.
HI, I was talking about using CaCo3 and Mgco3. then using HCl to get rid of co3, but I was wondering how much Cl that would add in the process.
well, I have amano shrimp, so I need 4-6gh.
 

Aleman

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Calcium chloride adds 2 chloride ions for each calcium ion. If you neutralise carbonate with HCl it will take 2 hydrogen ions to do so, which will leave 2 chloride ions ... So same thing really.

FWIW, calcium sulphate is soluble to 2.3g per litre so while it may be difficult to get it to dissolve in a bottle, it will dissolve freely in your water change volume ...
 

aquanoobie

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HI, I was talking about using CaCo3 and Mgco3. then using HCl to get rid of co3, but I was wondering how much Cl that would add in the process.
well, I have amano shrimp, so I need 4-6gh.
Hi
Adding HCl replaces CO3 with Cl2 and by doing so increases TDS. CaCO3, MgCO3, CaSO4, MgSO4 have lower TDS than CaCl2 and MgCl2. I know you don't want NO3 but the lowest TDS can be done with CaNO3 and MgNO3, avoiding SO4, Cl2, CO3. But plants need S as an essential macronutrient so adding some is good.

Since urea is organic molecule it does not increase TDS and it is an excellent N source.

When you look at very low TDS natural waters you will also see very low Ca and Mg levels. There is no way around it. Higher Ca, Mg, GH comes with higher TDS.
 

Easternlethal

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For those who play around with tds, what are the pros and cons in terms of plant health?

I am exploring reducing kh in my tank to grow more difficult plants but don't have the option of remineralising RO so just using leaves/peat moss or HCl. Will high tds make it harder for plants and outweigh the benefits of lower ch?

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