Borisfa
Well-Known Member
Multiple postage. Sorry.
Thanks @afr0byte and @ajdelange. More some questions:
My Water report is:
- Alkalinity: 186,5 mg CaCo3/L
- Bicarbonate: 225,1 mg/L
- Carbonate: 1,2 mg/L
- Calcium: 63,6 mg/L
- Magnesium: 3,4 mg/L
- Total Sulfate: 0
- Nitrite: 0
- Nitrate: 0,24 mgN/L
- Sodium: 4,8 mg/L
- Iron: 0
- Total Hardness: 172,9 mg/L
- pH: 7,5
My alkalinity: 186,5 mg/L or 3,73 mEq/L.
My Calcium : 63,6 mg/L or 3,18 mEq/L.
1) For a maximum alkalinity removal, Should I add about 0,55 mEq/L ou 11 ppm of some Calcium source (I need, at least, 74,6 ppm of Calcium)?
2) Considering I adjust my water to 74,6+30% = 97 mg/L of Calcium to remove Alkalinity and considering I need more Calcium for my mash (about needed 80 mg/L for mash) of Calcium on my mash, so I need add more 80 mg/L. Resuming, Will I need a initial Calcium content of 177 mg/L (97 ppm for decarbonating +80 ppm for mash) . Is this right?
3) Now about Lime, considering that is right remove 3,73 mEq/L of alkalinity, so I am need about 1,9 mmol/L of Lime, that represent 38 mg/L or 76 mg/L?
Thanks again,
Fabiano da Mata
Make sense my doubt? Or epsom, gympsum, CaCl2 labeled on spreadsheats already considere hydrate (water)?
Make sense my doubt? Or epsom, gympsum, CaCl2 labeled on spreadsheats already considere hydrate (water)?
Slaked lime absorbs CO2 out of the air and slowly converts to carbonate. Does this need to be taken into account when calculating the amount of lime to add?
Let's say I have a 5 year old bag of Mrs Wage's' Pickling Lime that I bought for making pickles. It's been stored in the original (opened) paper bag in a dry place. How much is still lime and how much is chalk?
Excellent work! The only caution I would have is that we would need to be slow during the assessment of the Total Alkalinity since it might take a few minutes for the chalk to dissolve during the testing.
It is, of course, important that the M titration be carefully done too but as the HCO3- + H+ --> H2O + CO2 reaction only involves ions (nothing needs to be dissolved) and the reaction of bicarbonate seems to be faster it is not so much of a worry as long as the P titration has completely dissolved the carbonate.I guess we would titrate down to 4.5 and then monitor the pH for several minutes longer. If the pH rises, a little extra chalk finally dissolved. Just titrate a bit more acid in to bring the pH down to the 4.5 target.
That's debatable. We are making the assumptions that the acid used to get to pH 8 corresponds to 100% (in milimoles) of the carbonate + 100% of the hydroxyl and not all the hydroxy is anihilated. At pH 8 the hydroxyl ion concentration is 1.0E-5 mmol/L, not 0, as we assume, but the error from hydroxy ions is much smaller. The acid used actually amounts to about 102% of the carbonate (titrate to 8.37 with a meter to get to 100% which is not enough to bleach phenolpthalein). Similarly, in going to pH 4.5 from 8 we assume that the acid consumed represents 100% of the bicarbonate which we have assumed is 100% of the carbonate. In other words we assume that M ~ 200% of the carbonate. In fact at pH 4.5 it represents 198.7%. At pH 4.4 it is 198.9% and at pH 4.3 it is 199.1%. Thus there are errors whatever end point we pick but as we go lower in pH it gets a little better. In that sense 4.3 is a better choice but not by that much. This is because the titration curve is flat (if you plot pH as the independent variable) here. It also means that if you have hit 4.5 it is only going to take a wee bit of acid to bring about an appreciable pH drop. So if you are using a buret or digital titrator then go ahead and try to get lower than 4.5 but do it very slowly.By the way, is 4.5 the proper target? I realize that the target for total alkalinity varies between 4.3 and 4.5. I'm guessing that 4.5 is fine since the chalk should be fully dissolved at that pH...right?
Enter your email address to join: