grassi Posted November 21, 2010 Share Posted November 21, 2010 If you own a good titration total hardness kit, like Elos or, better, La Motte you are probably testing your alkalinity pretty close to the real value. But how to be sure? How to test your test? (naughty) Test kits do a pH endpoint titration. That means that you add acid until the dyes turn color. When the color change you have a solution which is at ph 4,2 Now if you are lucky to have a ph probe, you can stick the probe in the solution so you can "test your test". Off course I'm assuming you just calibrated your probe with the 2 acid solutions (whistle) So, due to the nature of the titration you can either test your alk readings or either your ph meter, if you are sure you are reading the alk well. I really suggest a good kit for this, like La Motte, where you can have readings down to 4 ppm increments. The Elos one is good for fast readings in my opinion. Now the fun part. At this point if you were smart to buy a lab grade ph probe you can even set up your DIY alk test. You just need a bottle of 0.1 N Sulfuric acid standard and you can use it as a titrant. Take a sample of your water and stick your ph probe in it. Use a sample container that will easily contain the sample and the ph probe, like 100ml or more Fill a 5ml syringe with the acid and start dropping some into the sample You can stop when the ph probe shows 4,2 Now read how much titrant (acid) you had to add Now some math: if you added 3ml, then multiply it for your acid concentration (in this case 0.1) and then for 50,000 and divide the result by 100 for having the ppm 3*0.1*50,000 / 100 = 150 ppm NOTE I've found some information about this diy method on RC as well, where some source (Randy Holmes Farley) suggested to use standards instead of a ph probe, not being the latter a good gauge. But I think that for a quick reading the ph probe will work as well. 1 Quote Link to comment Share on other sites More sharing options...
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