What should be done if an ion exchange plant shows a finished hardness of 1 grain?

When an ion exchange plant shows a finished hardness of 1 grain, the correct action is to monitor and backwash if hardness levels increase. This response is appropriate because a finished hardness of 1 grain indicates that the ion exchange process is functioning, albeit at a low level of hardness removal.

Monitoring is crucial because it allows operators to detect any changes in the system's performance. If hardness begins to rise above acceptable levels, backwashing the resin bed can help to remove accumulated debris and restore the ion exchange process's efficiency. Backwashing is a common maintenance procedure that helps to ensure that the resin can continue to effectively remove hardness from the water supply.

It's important to note that while stopping the process or changing resin could be considered in more severe cases of malfunction, a finished hardness reading of 1 grain does not necessitate immediate drastic actions. Adding more soda-ash is not the solution for addressing ion exchange processes, as it is typically used in the water treatment process for precipitation, not for modifying the ion exchange system’s effectiveness. Therefore, the best course of action at this point is to keep an eye on the performance and take maintenance steps as needed.