Opinions please - does this sound right to you? For a 21 ft round 52 inch wall pool, the advertisement says" fits a 48 - 52 inch wall pool". I am being told by the manufacturer that the measurement from the bottom seam to the top (of the liner) should measure 53 1/2 inches. Now doesn't that seem to be a bit too short for a 52 inch wall pool? There will be virtually no overlap and room for the liner to settle as it fills.