<a href=showthread.php?s=&postid=11552669#post11552669 target=_blank>Originally posted</a> by Marko9
Also, I would not trust API as my test kit. They are not really known for their accuracy.
<a href=showthread.php?s=&postid=11560241#post11560241 target=_blank>Originally posted</a> by WarrenG
Mix up a gallon of salt water and test it. You should know what the test should show for calcium and mg.
For Alk, put 1.1350 grams of baking soda in a gallon of distilled water and its Alk will be 10. Compare your test results.
<a href=showthread.php?s=&postid=11563622#post11563622 target=_blank>Originally posted</a> by petes97
FWIW I haven't had any serious problems with API kits that are 1 year old or less. When they sit they tend to have problems. With the salifert problems API is a good cheap alternative.