Well here I go sticking my neck out again but the lucas formula isn't the best IMO. It eliminates the grow portion of the 3 part series. The grow portion is the one with 90% of the magnesium and other trace elements. By using the lucas formula you are almost guaranteed a mag. def. and will need to compensate with epsom salts. IMO using the 3 parts together (like they were designed) is best. Especially for newer growers who might not be able to diagnose mag def and hurt their yields. Just my opinion.