# Soft alkaline water?



## AlbaAquarist (19 Feb 2017)

While researching Dario hysginon I found that, according to SeriouslyFish, the water of their habitat in northern Myanmar is quite soft. However it is also neutral to alkaline in PH. I'm not particulary knowledgeable about water chemistry, but am I correct in thinking that this is due to a low ratio of acids to bases, despite the low buffering of the water?

If so how would I replicate this in an aquarium? More to the point is it necessary to replicate?  My understanding is that PH becomes a less useful measurement in very soft water and fish from these waters are accustomed to regular PH shifts due to the low buffering.


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## Henry (19 Feb 2017)

Liked due to being interested in this phenomenon myself.


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## rebel (20 Feb 2017)

Good question. I do know that liming water can achieve a low tds  with higher ph water. Lowish buffering.

Maybe slight bit of co3 in RO water?


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## AlbaAquarist (20 Feb 2017)

rebel said:


> Maybe slight bit of co3 in RO water?



By CO3 do you mean Carbonate? In what form? Would small amounts of Potassium Carbonate (K2CO3) result in an alkaline PH with a minimal increase in hardness?


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## xim (21 Feb 2017)

Edit: sorry, wrong lake, wrong data


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## dw1305 (21 Feb 2017)

Hi all,





AlbaAquarist said:


> the water of their habitat in northern Myanmar is quite soft. However it is also neutral to alkaline in PH. I'm not particulary knowledgeable about water chemistry, but am I correct in thinking that this is due to a low ratio of acids to bases, despite the low buffering of the water?


You can have soft alkaline water, it is quite unusual, but it does occur, particularly where you have tectonic activity.

I'd be tempted to ignore the pH and aim for water with a conductivity value of 150 - 200 microS. It would be  guess-work, but I think the fish will be fine. 

If I wanted to more closely replicate their natural water adding some combination of "Epsom Salts" (MgSO4.7H2O), potassium bicarbonate (KHCO3) and calcium chloride (CaCl2) to RO (or rain-water) should work until you get to the required conductivity. Again the exact ratio of the mix would be guess work.

If I ever manage to find any female _Dario_, I'm going to keep them in the same water as the other fish, just by cutting rain-water with our hard tap water, and then feed the plants via the Duckweed Index. I'll use the Ramshorn snails as an indicator of the carbonate hardness, and I'll aim to keep their shells slightly healthier (less white) than I do at present.

Mynamar lies along <"several tectonic plate boundaries">, and is being squeezed against the Asian craton, so a lot of basic (<"ultramafic">) rocks, from deep in the mantle, will be nearer the surface than normal.

Soft alkaline water is actually what a lot of people in the N. and W. UK get from their taps, now that their naturally acid tap water is treated with NaOH. Sodium hydroxide is a strong base, and all Na+ and OH- ions go into solution, raising the pH, but without adding any dGH or dKH or any buffering. 

My suspicion for the water in northern Mynamar is that it has a relatively small amount of carbonate buffering, derived from limestone rocks (calcium carbonate), but then diluted by heavy rain-fall, and depleted by the humic substances from fallen leaves etc. 

Again without knowing it may have more magnesium dGH than calcium, if the catchment flows over ultramafic serpentine rocks (or the soils derived from them).

cheers Darrel


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## AlbaAquarist (21 Feb 2017)

Thanks for the explanation Darrel. My tapwater is around 75 - 100 microS and I've got some MgSO4.7H2O and KHCO3, so I'll experiment with adding different ratios in a bucket and see what parameters I end up with.


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## dw1305 (21 Feb 2017)

Hi all, 





AlbaAquarist said:


> My tapwater is around 75 - 100 microS and I've got some MgSO4.7H2O and KHCO3, so I'll experiment with adding different ratios in a bucket and see what parameters I end up with.


That sounds a promising start.

Have you seen this <"breeding account"> for _Dario dario? _It doesn't mention water parameters, but fairly soft would be my guess. 

You could also try Colin Dunlop's "fishhut" facebook page, I know he has imported _Dario hysiginon_ in the past and he is likely to know what they need.

cheers Darrel


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## xim (21 Feb 2017)

Hi, the water parameters of Indawgyi lake (from page 55 of this document http://library.fes.de/pdf-files/stufo/cd-0768/thesis.pdf )

Using the WHO's terms of "total hardness" and "total alkalinity", the mg/l is CaCO3 equivalent. So I think they would translate to 3.9 dGH and 5.5 dKH. There are not calcium vs maganesium levels though.


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## AlbaAquarist (21 Feb 2017)

dw1305 said:


> Have you seen this <"breeding account"> for _Dario dario?_


Yeah I've read that breeding report, it was what got me interested in Dario dario when I was looking at small fish for a nano tank. It's a shame it's so difficult to find females, which is partly why I am leaning towards Dario hysiginon because I believe females are more common.


dw1305 said:


> You could also try Colin Dunlop's "fishhut" facebook page, I know he has imported _Dario hysiginon_ in the past and he is likely to know what they need.


I'm not sure why I didn't think of that before , I was actually considering trying to get the Dario hysiginon from Colin. I'll get in touch with him.

(edit)


xim said:


> Hi, the water parameters of Indawgyi lake (from page 55 of this document http://library.fes.de/pdf-files/stufo/cd-0768/thesis.pdf )


Wow, great information, that will come in handy. With Darrels point that the GH may be mostly Magnesium it should be possible to loosely replicate their natural water conditions.

Thanks for all the help.


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## dw1305 (21 Feb 2017)

Hi all,





xim said:


> the water parameters of Indawgyi lake


That looks promising. 

It looks like 150microS is in the right ball park.

cheers Darrel


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## dw1305 (22 Feb 2017)

Hi all,





AlbaAquarist said:


> With Darrels point that the GH may be mostly Magnesium it should be possible to loosely replicate their natural water conditions.


I'd go for a mix of Mg++ and Ca++, but I would suspect that the actual ratio doesn't really matter. I can add calcium carbonate (CaCO3) dGH/dKH hardness via a small amount of tap water, but if I couldn't I'd use "oyster shell chick grit"

In @xim's post the quoted BOD value for Indawgyi lake (0.8mg/l) is quite low, anything below 1mg/l indicates that it is unpolluted water source.  

cheers Darrel


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## AverageWhiteBloke (22 Feb 2017)

dw1305 said:


> Soft alkaline water is actually what a lot of people in the N. and W. UK get from their taps



I can vouch for that. I live in the most NW point in England and water comes out the tap with no hardness with a PH of 7.2


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## AlbaAquarist (22 Feb 2017)

dw1305 said:


> I can add calcium carbonate (CaCO3) dGH/dKH hardness via a small amount of tap water, but if I couldn't I'd use "oyster shell chick grit"



Had a chat with Colin, he said kept them in soft water with just enough coral sand to buffer the PH above neutral, so same idea really. I think i'll probably keep it simple and do the same. I have some aragonite sand for another tank, I presume since its CaCO3 it will be ok to use? If not I'll just get some oyster shell grit.


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## dw1305 (23 Feb 2017)

Hi all,





AlbaAquarist said:


> I have some aragonite sand for another tank, I presume since its CaCO3 it will be ok to use? If not I'll just get some oyster shell grit.


Coral (aragonite) sand is fine. 

The <"biogenic"> aragonite form of CaCO3 is slightly more soluble than the mineral calcite form. 

I usually suggest Oyster (or Cockle) shell chick/chicken grit because it is a lot cheaper then coral sand and widely available.

cheers Darrel


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