100% synthetic fibres are inorganic. Natural fibres in the sun blinds are
more or less organic and can therefore provide nutrients to the fungus
The spores also get nutrition from damp that are bound to the textiles fibres. Thereby they get good hold in the fine-threaded network and the growth starts.
The fungus recurs as long as the fibres contain any spores or remain of growth. The only way to surely prevent growth and future affections is to pre-treat the textile and to continue to treat it with Bensaltenside.
The sun blind then is disinfected and the fungus is sterilized and removed by rain or can be washed off. The protection is guaranteed to last for four years. Often longer than that.