Jack's classic isn't exactly intended to work with hydroponic setups. I'm sure it's possible as many people have done it, but it's not ideal.
Jack's hydroponics line, however, is different in that it provides a soluble form of calcium (calcium nitrate) and a low urea and ammonium content.
Soil based nutrients tend to get a bulk of its N from urea instead of calcium nitrate, and thus expecting the soil to provide calcium through limestone (insoluble). Hydro based nutrients get the bulk of their N and all their Ca from calcium nitrate.
Jack's professional hydroponics is a 2 part dry mix, where 1 of the parts is actually greenhouse grade calcium nitrate.
http://www.jrpeters.com/Products/Hydroponics.html