garden fence

Purchased these fence panels a year ago and fitted them without the need as I thought they were treated? I want to seal them now as they are getting some dark areas (see photos) what is this mould? Any suggestions as to what I should do? Sand it out? Treat it first with mould “stuff” I was...

Thought it was time to paint the fence as im getting through jobs quite quick whilst im in lockdown :D Got some Cuprinol Ducksback in Silver Copse as our fence doesnt get any sun in the summer its got a lot of algae on it what product would be best? I've seen bleach mentioned (not the most...