IPS Controllers IPS-M820L Automated Dual ORP and pH Controller for Muriatic Acid or CO2 allows operators to install multiple output devices on the same pool. With dual ORP, you can use a primary sanitizer, such as salt chlorine generator, with a secondary sanitizer, such as liquid chlorine, for rapid response to increased bather load. The second ORP may also be used as a safety backup (second pump and tank) for liquid systems. The M820 is compatible with all sanitizing methods, including liquid, tablets, granular, and salt chlorine generators and can be used with Muriatic Acid or CO2