Help please 3 fish down!

The salt added from a softener is about 12 milligrams, not a lot, this changed suddenly to 0 and the water became harder most likely with more magnesium and calcium. This is a parameter swing that I reckon would harm the fish, and possibly throw their system out of whack and killing th epoor sods, each fish has different tollerence to a cettain degree, depending on various factors but it looks like some were better equiped to survive the change.


For a want of any other explanation, when you top up the salt in the softener you again cause a sudden parameter shift and this can kill off the survivors.

Buut.. you could have run out of salt in the softener some time before the deaths



Mark

Where did the value of amount of salt added come from Mark? Which salt are we talking about? 12 milligrams? I don't have any specific data available on the hardness of various waters around ireland....but that value is a little questionable, and surely it would depend upon the volume of water coming throw the zeolites and into the tank.

Normally, these softeners rely on regenerating them by adding a saturated sodium chloride solution (but obviously this may be hava different regeneration method).
I would have thought that the normal procedure was to purge the system with some water before useage (and again, I don't know the specific of the machinery within that brand...so there may be a special by-pass system....but the basic chemistry remains the same as all).

Reading my post back there, I had thought I added some?? to my post, sorry, I am not so sure about what happens with the softener, but sodium of about 12mg per litre replaces the calcium and magnesium ions with the average softener, when I say salt I must be wrong, and please dont take my ramblings as any sort of scientific statements on my part, anything but:)

So a softener doesn't add salt to the water? I am asking and not neing a smart azz:)


Wouldn't be the first time nor will it be the last time I am educated for free on ITFS:)


mark

You'd missed out the 'per litre' bit in the post 3 posts up.
I thought 12mg was a bit too small as a generalisation, but 12mg per litre would be in the right order of magnitude.
(I was actually wondering if you'd found one a spec for a water softener making miracle claims on human health....there's a few out there making silly claims. )

In principle, you're right......if the hardness if caused by say calcium or magnesium chloride (both are salts) then for every molecule of, say, calcium chloride the softener will output 2 molecules of sodium chloride (assuming 100% perfect exchange). It will do the same with magnesium chloride. If the concentration of calcium or magnesium chloride in the hard water is high then the output of sodium chloride will be proportinally higher upto the resin becoming exhausted.

If the hardness is calcium or magnesium bicarb then the softener will release sodium bicarb (which will then go on and do whatever it will do in the water).

There may well be a residual release of sodium chloride from the re-charging of the resin.

With de-ioniser units, however, they will adsorb the anions as well and hence the output water will not contain the chloride or sulphate or bicarb anions...and so with the electrical charges balanced within the unit: nothing is released.

Ancient technologies are still used (basically a water softener is clay from the garden...but in a nice composition !!), but in recent years there has been some great leaps in zeolite technology for all sorts of exchange reactions or complete adsorption of chemicals. If a softener contains non-ancient technologies then they well do much more than the basics.

Alan alerted Platy on a problem that was a big fish-keeping problem many years ago.....aquaists would read that fish such as Discus need 'Soft Water' and naturally get a readily available sodium aluminium silicate water softener (usually the Permutit domestic unit for washing machines) to soften the water.
Not a great idea.. I even remember some fish-shops selling those types of softeners (no wonder people were finding Discus hard to keep !!!). It's not necessary the sodium chloride output that is the problem, it is more the unbalanced water that is the problem.

That is one reason I, for one, am always a bit concerned on fixations on a single item within water chemistry.


ian

An education as always Ian, glad you could assemble a little of my gibberish:)


I guess what I am getting at is the balance of parameters, also if water ph is 6 comin out of the tap, thats low would there possibly be lots of CO2 in there preventing aeration of the water, 6 is low out of th etap indeed to my 8.2


Mark

Salts of strong acids do not normally contribute to the pH in themselves. So exchanges regarding the chlorides and sulphates salts in hard water to produce sodium chloride should not contribute to the pH per se.

HOWEVER, a measured or calculated pH is somewhat dependant on the total concentration of solutes as pH is not actually about concentration of hydrogen ions but is about the activity of the ions; the activity may be affected by a number of factors inlcuding temperature, pressure, solubilities, salting-out, conductivity, and presence of other components affecting equilibrium etc etc., and the hydration level of different ions also affects pH……ooh, I actually forgot to mention that the concentration of water in water is important (eg salt water has a lower concentration, or activity, of water than does freshwater)
Now, that bit is rather complex....and to go into explaining that would take me a few days of typing. But, hopefully....you'll get the picture.

The other thing that is important to note is that when we measure pH in our tanks, we are not necessarily measuring the pH that the fish experiences. The fish experiences the pH at the surface interface as well as any bulk phase pH.....again, that is in the realms of electrodics and interface redox potentials. I have a great interest in that....but I guess that many are not.

Now....when dealing with hard water, we are also dealing with salts of weak acids (eg calcium or magnesium bicarbonate). [carbonic acid is the source acid and is a weak acid….no matter how much is added]
As opposed to strong acid salts, weak acids salts tend to be alkaline (the extent is depending upon the pKa of the source acid). Ie they themselves directly contribute to the pH in addition to affecting pH by their presence as a solute.
Although these are alkaline salts, they would actually be acids in the presence of something like ammonia!!!

What happens now? In the exchange of the softener, the calcium is exchanged for sodium to produce sodium bicarb…this has different solubility and stability to calcium bicarb and so that would also affect the output pH.

Aaaagh, but……bicarb and carbonic acid are in equilibrium with CO2. Addition of CO2 will thus affect the dissociation of the bicarb, and varying the solubility of the bicarb will affect the contribution of CO2 to the pH. In other words, there is a nice pH buffer system set up…..but with slightly altered parameters based upon the differing solubilities and stability of the calcium (or magnesium) incoming bicarb salt and the sodium outgoing bicarb salt.

I know that you like this science stuff Mark….so I expanded that for you a bit, but not too much as I’m sure many will consider this to be a bit boring.

There is another caveat here….one can go into lots of theory and show why some unexpected things can be explained, but in many cases the fine detail becomes a whispered conversation in the bigger picture of things (especially as we are hopefully only ever dealing with very dilute systems with a high water concentration).

"Mark reads above furrowing his brow in a vein attempt to understand a lot of Ians info"

It seems with the water softener and other water parameters were so that fluctuations of certain elements of the water make up would more than usually adversely affect the fish.

By that I mean, with the normal freshie setup the water content is high. Maybe the water content was not so high in this scenario and thus reduced the capacity to buffer changes normall accomodated with high water content freshwater, killing off the fishes. Things like extra high amounts of C02 in the tap water and the softener running out of salt. Again veinly trying to understand:)


Mark

i think ill need to become a chemist to understand half of this stuff

alan.s wrote:

i think ill need to become a chemist to understand half of this stuff

Join the club Alan:) Cant' A great insight none the less into things I otherwise would not have been aware of, even if you don't get it all there is some pretty good info even us layman can understand to get a beter picture of what might have gone wrong and what might go wrong in future.


mark

oh big time mark i think its broadened my mind and given me a deeper understanding into the chemical problems that can effect my pets! don't know if I'm more worried about em now than i was before thanks again for all the help lads i appriciate it!
Al

alan.s wrote:

i think ill need to become a chemist to understand half of this stuff

You're never too old to think about signing up for a degree in chemistry (or che-mystery as JohnH says).

How's your fish now Alan?

@Mark....surely, but surely, you're not trying to tempt me expand on each comment above.

If only real life were as simple as the chemistry that I learned in school (or for much of the degree for that matter).

For some reason, water itself is so often ignored when talking about water chemistry.....it is a chemical, it is a very powerful reagent in biochemical reactions,the concentration of water in water varies when something is added, it is much much more than a solvent......it's actually quite magical.

I'm very much of the opinion that the redox potential of water is a parameter often ignored....yet it is not ignored by living systems. Sometimes we find fish being quite happy in what is considered a 'non-ideal' pH yet thriving.....maybe the redox sorts everything.

ian

igmillichip wrote:

Sometimes we find fish being quite happy in what is considered a 'non-ideal' pH yet thriving.....maybe the redox sorts everything.

ian

I'll addto that some credit to the adaptability of a fish and recognition of steady if not perfect parameter importance:)



Mark

Mark. wrote:

igmillichip wrote:

Sometimes we find fish being quite happy in what is considered a 'non-ideal' pH yet thriving.....maybe the redox sorts everything.

ian

I'll addto that some credit to the adaptability of a fish and recognition of steady if not perfect parameter importance:)



Mark

And might that adaptability be due to the ability of biological systems to shift redox systems such that the overall 'at the end of the day' result is the same irrespective of path. eg you could go A to Z or A to E to C to Z ?
Mother nature has some tricks up her sleeves....she's actually having a laugh.

Touche:)


mark

@ Ian, I think I undehstood some of that post. Some salts are more active in effecting Ph than others? So total hardness of TDS doesn't go hand in hand with higher ph?

The reason I ask, is that after bothering the very patient guys in Seahorse today, I discovered the following:

Untreated well water - carbonate & total hardness = 14 & 16. ph - 7.5 - expected higher ph with those hardness values.

Post treatment (with water softener & iron removal) 2 & 2 - ph - 8.2. Wasn't expecting that at all.

Is likely due to the sodium post treatment? Is it not detected by hardness tests or is it in low amounts but highly "charged"?

Jim wrote:

@ Ian, I think I undehstood some of that post. Some salts are more active in effecting Ph than others? So total hardness of TDS doesn't go hand in hand with higher ph?

The reason I ask, is that after bothering the very patient guys in Seahorse today, I discovered the following:

Untreated well water - carbonate & total hardness = 14 & 16. ph - 7.5 - expected higher ph with those hardness values.

Post treatment (with water softener & iron removal) 2 & 2 - ph - 8.2. Wasn't expecting that at all.

Is likely due to the sodium post treatment? Is it not detected by hardness tests or is it in low amounts but highly "charged"?

I was in seahorse this afternoon.

This is were some of the old myths about pH and hardness come in.

It is not necessarily the sodium levels that cause such a increase in pH. You've got a 5-fold increase in alkalinity (or, in other words, the free hydrogen conc is reduced to 1/5th of its original conc).

It is quite common for various 'softening' methods raise the pH.
eg sodium carbonate crystals (bath salts) soften water but raise the pH.

It is easy to have softwater and have a high pH eg add caustic soda to pure water.
It is also possible to have hard water and low pH. eg lots of calcium chloride added to vinegar.

It is when we come to carbonates that things get a bit tricky. Carbonates are salts of a weak acid (carbonic acid).
In the cases of weak acids and weak bases, a value of the pKa becomes important.
The degree of dissociation of a weak acid is pH dependent even though the acid itself will contribute to the pH directly by dissociation.

If, say, a weak acid has a pKa of 7.8 then at a pH of 7.8 in water, half of it exists as the molecular acid (ie thing added) and half exist as the salt (a bit simplistic, but suffices). If we add, say, a small amount of sodium hydroxide, then more of the molecular acid will dissociate to produce more salt and the pH will increase. By adding some of the salt of the weak acid will, however, actually help to resist a change in pH when a small amount of sodium hydroxide is added.
Why? because the system wants to try to get back to equilibrium....the equilibrium lies in a region shown by the pKa.
This weak acid/salt mix is the basis of a buffer solution.

But carbonic acid is not as simple as that when it comes to actual measurements.....salts of carbonic acid may be carbonates or as bicarbonates. And when in equilibrium with carbon dioxide, there is an ambiguous meaning of the pKa value.
Carbon dioxide is in equilibrium with carbonic acid; and carbonates are in equilibrium with the bicarbonates. That means that carbonic acid effectively has two dissociations to form salts.

OK, so in not really covering the theory of carbonic acid to any extend, back to hardness and softeners....

Calcium bicarbonate is soluble; calcium carbonate is not (or only partially) soluble. Calcium bicarbonate will directly affect the pH as it is salt of a weak acid.
In an ion exchange water softener, the calcium is swapped for sodium. The output is sodium bicarbonate....but bicarbonate is in equilibrium with carbonates....however, for sodium, both bicarbonate and carbonate are soluble. Hence, you may get a different degree of buffering going on (in the calcium system....if the calcium forms insoluble carbonate then it is almost removed from the equation!!....that is why boiling hard water removes temporary or carbonate hardness).

Oh and wait...bring in another effector.....the atmospheric pressure of carbon dioxide. !!! no we won't go there, but the fact that carbonic acid buffering is a key buffer of blood indicates that someone (mother nature) understands and can react to the unusual equilibriums with carbonic acid.

Does any of that make any sense?

Now, hardness test kits are a bit questionable……sometimes you can get a carbonate hardness that is higher than the total hardness!!! How? Well, it may well be that the carbonate hardness is testing for something that doesn’t actually cause hard water (sodium bicarbonate is not a causal agent of hard water, but if carbonate test kits detect it then it will appear as a positive reading of hardness).

Salt concentration will also affect pH meters. (this is quite a complex bit of chemistry).

Much of the confusion with all of this has been the historic focus on hardness and pH and the written emphasise that hard water is generally alkaline. When the truth is different. Soft/Acid water and Hard/Alkaline water are really ‘generalisation’ on water types….there is nothing unusual about Hard/Acid water nor Soft/Alkaline water.
The analogy of the pairings may be saying ‘boy racer cars always break speed limits’….well it depends on if the boy racer car has a boy racer in it or not !!

ian

Thanks Ian, I need another cup of tea and a quiet spot to read it again, but I think I Understand bits of that !

The bottom line seems to be that the untreated water is fine for Tangs and malawis, with some more slight adjustments.

The reality of the treated stuff is probably that it has tons of sodium bicarbonate not picked up by the gh test, so from the perspective of fish it's still hard. I'll leave some out in a tank for a few days and see if the ph drops, just to see.

solution is probably RO followed by remineralisation or dilution with untreated, if I want to keep discus or similar.





Dear Santa, I've been a good boy and would like an ro unit this Christmas. Does Rudolph do plumbing?

think i have a bare understanding but will pass on the chemistry degree (my friend has one and one of us is enough ).
Fish were all fine last time i saw them(up in Dublin with the missus). hopefully all will be well when i get back. heading on hols to states on fri and hoping they will be ok while im gone. a friend is going to keep an eye on the place and fish for me whilst im away.
Al