there is no doubt that chelated iron is more effective than few iron nails buried in the gravel, but you need to dose that on a regular basis.
Iron nails cost almost nothing and are available for the plant roots all the time. It is a fact that in my over 30 years plant aquarium experience I have verified times and again their effectiveness. when I have those in the gravel I do not experience iron deficiencies in my plants.
Many plants strongly grow their roots firmly attatched to those, expecially the plants you give enough time to grow in the same spot. ( plants talk to us, but we need to listen...... it is clear they love those nails they firmly grab them)
Iron nails cost almost nothing and are available for the plant roots all the time. It is a fact that in my over 30 years plant aquarium experience I have verified times and again their effectiveness. when I have those in the gravel I do not experience iron deficiencies in my plants.
Many plants strongly grow their roots firmly attatched to those, expecially the plants you give enough time to grow in the same spot. ( plants talk to us, but we need to listen...... it is clear they love those nails they firmly grab them)