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You vote always counts and it will grow, there is a dust rule that is a post is under 2c then it will not get paid out, this applies to ones that may even look like that have 0.02c as it really could be 0.01899c. Confusing I know, so for you there would be no use in upvoting a comment that does not already have at least 0.2c until your SP grows, post quality and it will move on up :)

So.. I can upvote the post instead? Even though my vp under 80. Thank you.

I would try to keep my VP above 70% at all times so 80% is ok. Just dont waste it on comments that wont get paid out due to the dust level :)