From: '''newspam'''@nezumi.demon.co.uk   
      
   On 14/11/2018 01:39, Oumati Asami wrote:   
   > On 13/11/18 18:00, Martin Brown wrote:   
   >> On 11/11/2018 15:44, Oumati Asami wrote:   
      
   [snip]   
      
   >>> If the ppt only occurs above a threshold, it explains why more   
   >>> hypochlorite causes the ppt. I just wonder where the carbonate came   
   >>> from. Can it come from rain? I thought acid rain usually is caused by   
   >>> H2SO3, not H2CO3.   
   >>   
   >> CO2 is in the air and dissolves in water. The reason your pool goes   
   >> cloudy is that water can dissolve a certain amount of calcium as the   
   >> soluble bicarbonate ion but if you add a lot of it (calcium) all at   
   >> once then there may not be enough CO2 to go around and so some ends up   
   >> as a calcium carbonate precipitate which may gradually redissolve over   
   >> time.   
   >>   
   >> You are going to get a gradual build up of calcium in the water longer   
   >> term.   
   >>   
   > I need to have the chlorine generator fixed soon.   
   >   
   > Wikipedia says the solubility of calcium carbonate is 13 mg/L. Somewhere   
   > on the web it says the calcium concentration needs to be between 200 and   
   > 400 ppm. Other than carbonate, is there any other calcium salt that has   
   > lower solubility? I'm thinking of adding an anion to precipitate   
   > calcium. I can't afford to use ion exchange to remove calcium.   
      
   Calcium carbonate is about the least soluble of the calcium salts. The   
   calcium dissolved in your swimming pool is present as the *bicarbonate*.   
      
   See https://en.wikipedia.org/wiki/Solubility_table#C   
      
   --   
   Regards,   
   Martin Brown   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)