VEVOR Whole House Salt Free Descaler, Water Filter for City Water, 600,000 Gallon Whole House Water Descaler for All Kinds of Plumbing Pipes, 1" NPT & 3/4" NPT, for 2-3 Person Family

It does not filter scale, but prevents scale from forming, making it difficult for water to scale. It also depends on the specific ingredients. If the hardness is really high, the effect may not be too obvious.