CoyoteOldMan BTW, I wouldn’t put the Mg solution through another sodastream process; the idea is to have ‘just enough’ hydrocarbon ions to create Mg(HCO3)2 from the amount of hydroxide you added; if you add excess CO2 you end up with water that may be too acidic for optimal ‘coffee use’.
Thanks CoyoteOldMan! Please see my below reply and questions. Sorry for the long post that follows! It took a number of words to explain what I am doing and address the issues.
Hmmm … My SodaStream comes with 1 liter bottles. But as per the recipe, I placed 500 ml zero water in the 1 liter bottle, and screwed the bottle into the SodaSteam unit. You then lift a top lever until the bottle fills with CO2 and the unit makes a buzzing sound, which is excess C02 escaping from the bottle. But it took ALOT of CO2 to fill the empty ½ liter of space in the bottle; the unit really is not meant to do that; you are supposed to fill the entire bottle to a top line. Anyway, interestingly the water did not fizz as much (as it usually does), probably because the CO2 enters the bottle from the top of the unit and did not immediately percolate through the water. Rather the gas filled the entire top half of the unit before it made contact with the water. I then placed the 1.44g of magnesium in the supposedly carbonated water. As it did not seem to be fizzing much, I ran the C02 into the bottle a 2nd time.
Sure went through alot of CO2! So I am thinking I will fill the bottle with 1 liter of distilled or Zero water and 2.88g magnesium hydroxide, to make 1 liter of that concentrate.
Should I ditch my current ½ liter batch of magnesium hydroxide? I am however guessing that not alot of CO2 was actually introduced into the water, as the water was not fizzing as much as it usually does. Still, I suppose I should ditch this batch, right?
BTW, I left this bottle (the ½ liter of concentrate in the 1 liter sodastream bottle) to sit overnight, so that any undisolved magnesium hydroxide would settle to the bottom of the bottle. I just inspected the bottle and see a very very small quantity of grains at the bottom if the bottle. Probably less than 0.1g. The water is barely fizzing (it is usually fizzing more), but I took of the bottle cap to let any residual CO2 escape.
Questions: what should I do if I see some magnesium hydroxide at the bottom of a bottle? For the current ½ liter concentrate (in the 1 liter bottle), I don’t think that I should or will run CO2 through it again. For a new 1 liter batch, do I: run the CO2 through it again (which as you say would result in excess acidity)? I think I should not.
Or alternatively I could filter the concentrate through a paper filter or a cloth filter or a metal filter, all of which I have used for making pour over. Is this a good idea?
Question: How long should I leave the bottle to degass and to allow any undissolved magnesium hydroxide to settle to the bottom?
Now I can/will test in any event test the acidity of the water, using my API test kit at 4X resolution, as you or Rob1 suggested, for greater accuracy.
Sorry for the long post! It took a number of words to explain what I am doing and address the issues.