Guys, unless I missed it, nobody has said anything about Magnesium. Coraline is a great consumer of Mg.
Sentari if I were you I would acurately mesure your Mg (TM test kit works well) then if its low add a Mg specific additive.
Good advise - magnesium is also pretty important, and I should have pointed that out earlier - thanks for the advise, Rob
Hennie