Welcome to TFP!
Calcium scale presents as raised rough patches on the plaster and will be random across the pool. Generally, a scale line will show at the waterline on the tile first and if you have SWG the cell will scale and require regular cleaning. I have diligently maintained my CSI between -0.3 and 0 for five summers and haven't ever had to clean my SWG cell. If the CSI has been kept below +0.6, or even better under +0.3, then it isn't possible for the pool to scale. The SWG cell still might scale but scale won't build up on the plaster.
More about scale here, Pool School - Calcium Scaling
Calcium scale presents as raised rough patches on the plaster and will be random across the pool. Generally, a scale line will show at the waterline on the tile first and if you have SWG the cell will scale and require regular cleaning. I have diligently maintained my CSI between -0.3 and 0 for five summers and haven't ever had to clean my SWG cell. If the CSI has been kept below +0.6, or even better under +0.3, then it isn't possible for the pool to scale. The SWG cell still might scale but scale won't build up on the plaster.
More about scale here, Pool School - Calcium Scaling