• You are viewing the forum as a Guest, please login (you can use your Facebook, Twitter, Google or Microsoft account to login) or register using this link: Log in or Sign Up

Soft alkaline water?

AlbaAquarist

AlbaAquarist

Member
Joined
1 Oct 2016
Messages
27
Location
Highland, Scotland
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.
 
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?
 
Last edited:
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?
Click to expand...
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
 
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.
 
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.
Click to expand...
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
 
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.


parameters.jpg
 
dw1305 said:
Have you seen this <"breeding account"> for Dario dario?
Click to expand...
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.
Click to expand...
I'm not sure why I didn't think of that before :facepalm:, 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 )
Click to expand...
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.
 
Last edited:
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.
Click to expand...
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
 
  • Like
Reactions: xim
dw1305 said:
Soft alkaline water is actually what a lot of people in the N. and W. UK get from their taps
Click to expand...

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
 
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"
Click to expand...

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.
 
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.
Click to expand...
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
 
Hey @dw1305 , sorry to revive a thread but… I am not a chemist and while I have a vague idea about bases and acids (a levels, yawn) I basically know nothing.

My water has this, dGH around 1.5, ph 7.8, sometimes 8.2.

I understand that the water is likely dosed with NaOH, but will the buffering of ph reduce as water ages? Or is there something else I can try to get a stable slightly acidic ph? I’m considering co2?

I don’t really want to mess with tap water.. but 😬
 
Hi all,
castle said:
..... My water has this, dGH around 1.5, ph 7.8, sometimes 8.2.

I understand that the water is likely dosed with NaOH, but will the buffering of ph reduce as water ages?
Click to expand...
It Is a bit of a strange one. The sodium hydroxide (NaOH) is strong base and is disassociated into a Na+ and an OH- ion.

You only need a very small addition of NaOH to raise the pH, and that means you only need a small addition of acid to "overwhelm" the bases and cause the pH value to fall.

Personally I just ignore pH in soft water, I'm only interested in the alkalinity. The parameter of interest is @_Maq_ 's <"acid neutralizing capacity"> (ANC) and in this case it is a small value, you just need to add enough H+ ions to neutralize the added OH- ions.

Cheers Darrel
 
Last edited:
dw1305 said:
Personally I just ignore pH in soft water, I'm only interested in the alkalinity.
Click to expand...
This is a bit strange because if by 'alkalinity' you mean the various forms of dissolved inorganic carbon (e.g bicarbonate) then at equilibrium with atmospheric CO2 the pH and alkalinity are completely interdependent. Neither is really affected by 'hard' or 'soft' water if by that you mean the presence of divalent cations Mg+2, Ca+2 etc.
 
I’m wondering if I should make a continuous ph probe attached to a pump which adds say 10ml of hydrochloric acid until ph is at say, 5?

Wondering if this is a bit mental tho? 😅
 
You must log in or register to reply here.
Back
Top