Hi all,
Said most tanks had shed loads of salt in them and that most commercial remineralisation products have a high level of sodium in them.
I think this will be true for a lot of shops where they still routinely add "therapeutic" salt. I also think this is true of a lot of commercial mixes. We had an answer, on another forum, from "Kent", where they said their RO re-min salt mix mirrored the salt levels in fishes and contained "carbonic acids and monosodium salts".
They also supplied an ingredient list:
"Kent pH Stable"
Chemical percent
Sodium bicarbonate <90
Sodium carbonate <20
Magnesium carbonate <5
Sodium borate decahydrate (borax) <5
So basically sodium bicarbonate ("bi-carbonate of soda"), and sodium carbonate ("washing soda"), both of which will increase the GH and pH, but not the KH (they will disassociate to Na+ ions).
The small amount of magnesium bicarbonate will increase the KH marginally (Mg2+ ions), but it is really in there as the "anti-caking" agent, they add it to table salt "Because of its water-insoluble, hygroscopic properties MgCO3 was first added to salt in 1911 to make the salt flow more freely." It is also the ingredient of heart-burn tablets "milk of magnesia".
The contains carbonic acid bit is misleading (and belongs here) it comes from this "magnesium carbonate can also be synthesized by exposing a magnesium hydroxide slurry to carbon dioxide under pressure (3.5 to 5 atm) below 50 °C, which gives soluble magnesium bicarbonate":
The "borax" (sodium tetraborate decahydrate) is actually the pH buffer, it is a very alkaline buffer and would buffer the water up to about pH8 or higher if there was more of it. The "decahydrate" bit just means the salt contains a lot of water (Na2B4O7·10H2O), it's the 10H2O.[/i]"
I cut with a bit of tap but as far as I know my tap is stable. However, I also dose EI in my main tank and have been wondering if this is all I need. I.e. surely there is enough calcium and magnesium etc in EI mixes for what the fauna need? Maybe even in TPN? In addition I am concerned about the build up of all of this which is exacerbated by the use of the tap water. My TDS just after a 40% water change (but including 1/5 the weekly dose of ferts) is around 170. A week later it is 350+. Maybe just going pure RO is fine?
If I lived in London I would definitely try and put as little tap water in the tank as possible, as the tap water is mainly fairly nasty. I don't see any reason why you can't just use 100% RO, if you are adding TPN or using EI etc. You could always add a small amount of potassium bi-carbonate if you were worried about the dKH being too low.
cheers Darrel