Pentair 522621 Intellichem® Controller with Acid Tank per Tank Mounted Pump - Automatically monitors pool pH and sanitizing levels and delivers just the right amount of chemicals. It can work independently or in conjunction with other Pentair automation products. Its built-in Langelier Saturation Index calculator lets pool owners know when the water is in or out of balance, and uses the same technology found in commercial installations, water parks, hotels, and community pools.