Just moved and the new house has a salt cell. The previous owner said the pool guy jus added salt to the pool, but the Aqua Logic display says its at zero. When I tested the saline it is at 4200! The salt cell looks good, clean, no build up. The cell is not producing chlorine, so I have been using liquid chlorine. I need to dump water to lower the salt level. How much water do I dump? I assume there is something wrong with the display, that it reads zero when it is actually very, very high.