The Dennerle Perfect Plant System Set contains 3 products to get your planted aquarium off to the best start… E15 FerActiv 10 tablets V30 Complete 25ml S7 VitaMix 25ml. The Dennerle fertilization system consists of a basic fertilization and a supplementary fertilization stage. The basic fertilizers E15 FerActiv iron fertilizer and V30 Complete special fertilizer introduce into the aquarium those nutrients which can remain present for extended periods. The supplementary fertilization using S7 VitaMix provides those nutrients which are consumed rapidly and of which a long-term supply cannot be built up. S7 VitaMix is therefore added on a weekly basis.