Here is the link to MSDS pdf of the 50 pound bag I bought for $8.88
http://www.homedepot.com/catalog/pdf...e27cd5efaa.pdf
It seems it will last me for a looong time (smile)
According to the MSDS it has over 50% Ca(OH)2 and over 35% Mg(OH)2), less than 5% of MgO, less than 3% of CaCO3 and less than 2% of SiO2.
I added some Muriatic Acid to lower Ph and I will test it again tomorrow.
It seems that Leslies has the strongest Muriatic Acid available, 32%, compared with 18% in Home Depot and Lowes, and price is just $2 more, so I tried that (smile)