02-04-2005, 11:09 AM
Join Date: Oct 2004
Location: San Jose, CA
Originally Posted by Edward
Surely you already have a GH kit, so the only one you would need to add is a $6 Ca test kit. You can get Mg concentration by testing for GH and Ca, then calculating the Mg. Water hardness, magnesium and calcium
The only problem is, my $6 Ca test kit(AP one I think) was for SALT water, and I know for sure its reading is way off for freshwater, because I did an experiment by adding NaCl into the water to mimic salt water to some degree, and Ca reading is very different. In addition, it is in increments of 20 ppm. So combined resolution of GH(1 deg) and Ca makes accurate determination almost impossible. Or can you suggest a good, cheap Ca test kit for freshwater?