Two year old IPE deck - use whitener?

Hi,

my first time staining my IPE deck (haven't stained it yet, two years since installed). It's situated under an oak tree so usually in the shade but plenty of leaves and dirt falling from the tree.

If I understand correctly, I need to clean the deck properly before applying stain. 

My question is: do I also have to use whitener *after* I clean it? If so, which whiteners are recommended for IPE?

Sorry if already asked - this is my first time doing this.

Thanks!