Salt build up

newbie help needed

coming into my last week in flower and have been hand feeding they are potted in canna coco and i have noticed the coco on top is covered in a white residue mabe build up of salts.

just wondering should i scrape all this off before flushing and how should i go about flushing

thankfull for any responce

Could be mold, scrape it off dont touch the plant wash your hands and blow some fans in there.

is it common to have a lot more salt build up when hand feedind

is it salt buildup when you spray water on top and it kind of glides over it?

cleaned it off seems ok cheers still puzzled