Owing to present and expected future regulations on the use of polluting antifouling compounds, there is a growing need for alternative methods for the prevention of biofouling. Some experiments on the effect of iron benzoate, as a possible biocide agent, on nauplii of Balanus amphitrite were carried out. This pigment was used because it is rapidly hydrolysed and consequently it produces a pH decrease. Although anion benzoate has an intense narcotic effect on nauplii, the results clearly demonstrated that the combined action of this compound and a pH decrease (generated by iron benzoate hydrolysis) produce a pronounced antifouling activity, i.e. the synergic effect is greater than separate effects.