Sources for chemicals

["James Purchase" <jppurchase at rogers_com>]

Rachel mentioned buying her chemicals from a hydroponics store. Good plan,
but make sure that you confirm exactly WHAT you are buying. Many fertilizer
chemicals are sold in various forms and quite often the generic name that
the store uses doesn't match the true chemical name (and thus the chemical
formula).

For example, I bought the 6-Pack for nutrients from Homegrown Hydroponics
here in Toronto. One of the containers says "Calcium Nitrate" (handwritten
on the label by the store). The Homegrown Hydroponics website describes this
as "CaNO3". As molecules are electrically neutral and the calcium ion
carries a charge of +2 while the nitrate ion carries a charge of -1 this
"formula" is clearly wrong. The simplest correct chemical formula would be
Ca(NO3)2. From looking at several different chemical lists, I realized that
"calcium nitrate" could be obtained in a variety of forms - both anhydrous
and hydrated to varying degrees. When I emailed Homegrown Hydroponics and
asked the proper chemical formula for what they were selling, to their
credit they quickly supplied the answer (Calcium Nitrate Decahydrate, which
has a chemical formula of 5Ca(NO3)2 + NH4NO3 + 10H2O). But if I hadn't
asked, I never would have known.

Having the correct chemical formula for what you are using is important if
you are using percentage composition to determine your dosing levels.

Be aware.....

James Purchase
Toronto