Hi all,
I would be over joyed if my tap water changed as your tap water did. You are over thinking the "problem." Your techniques intended to simulate the dry and wet seasons are merely just that; Simulations and what is the real basis that the change in seasons affects the timing of breeding Amazon basin fishes? Lots more fresh water and a more abundant food supplies for adults and fry. The actual water chemistry down there never deviates very much.You should get the desired effect by keeping fish with a touch of benign neglect; make fewer and smaller water changes then abruptly step up your game and increase the frozen and live foods. You will achieve the desired results which is simply a change of conditions that stimulate the fishes breeding conditions.
I agree with Apistomaster and MatsP, your water is pretty good and I'd be quite happy to use it how it is.
Indeed - which is exactly why you want it. You would get bicarbonate from calcium carbonate when dissolved in water (in fact, calcium carbonate as such doesn't dissolve in water at all - only the bicarbonate form does, unless I've completely misunderstood things). If you have NO bicarbonate, your pH will be somewhere between 4.0 and 5.0, which I doubt you actually want. It only pushes TOWARDS 8.2, and if you use the right amount (aiming for a KH of around 3 -> pH of around 6.5-7), it will be fine
What we are trying to say is that you can add compounds to your water to achieve any parameter that you want, but this has potential complications, unless you fully understand these. It is almost always better to work with what you've got, and then look at the other issues that may be effecting your fish (like MatsP suggests).
Sodium naturally is found in 2-4 times the concentration of Magnesium and only calcium is found in greater concentrations. Eliminating sodium would be making the water unnatural.
I'll just do this one, this isn't relevant to most of S. America, the water is almost devoid of
all cations (sodium, calcium, magnesium, potassium etc.), and any small amount of carbonates will have been entirely used up by the humic acids in the water (from fallen leaf litter).
Good link earlier in the post: <
http://www.fao.org/docrep/003/T0537E/T0537E02.htm>
You can't really explain this without some chemistry, but I'll have a go:
Some compounds are relatively straightforward and will disassociate immediately (they are completely soluble) like NaCl (Na+ Cl- ions) (or MgSO4.7H2O) and they will raise the conductivity, and (dependent upon whether they are H+ ion acceptors or donors) alter the pH either up or down. Other compounds like CaCO3 are "buffers", where their solubility changes around a pH value with compounds able to go in and out of solution, but usually with some proportion of compound in the undissolved state.
The reservoir of carbonate buffering is the dKH, and that is why it is important.
These reactions e.g. NaCl disassociating to Na+ & Cl- is an example of an acid / base interaction, but we can look at a specific acid / base pair and the pairing that is probably most relevant to us is the reaction between CO2 and carbonates, this is slightly complicated by the disassociation into bicarbonate and carbonate, but starts with:
CO2 dissolving to form carbonic acid (H2CO3):
CO2 + H2O is in equilibrium with H2CO3.
You can drive the equation in either direction by adding either CO2 or a source of carbonates:
CO32− +2 H2O ↔ HCO3− + H2O + OH− ↔ H2CO3 +2 OH−
&
H2CO3 +2 H2O ↔ HCO3− + H3O+ + H2O ↔ CO32− +2 H3O+
In very hard carbonate rich water (water with a high dKH "K(c)arbonate Hardness") you have a large supply of carbonate, this is "buffering", the potential to neutralise acids (or technically to accept H+ ions). The dKH is from the carbon dioxide (CO2, but dissolved as H2CO3 in rainwater) reacting with limestone (calcium carbonate (CaCO3)) to form soluble calcium bicarbonate (Ca(HCO3)2) and giving you a large reserve of carbonate buffering in the water.
cheers Darrel