The Importance Of Automated pH Control

In Blog, Controllers by Timothy Petsch

Most commercial pool professionals know that pH is the most important measure for water chemistry. They also know that it is darn near impossible to control by hand – it’s like trying to make sense of a bowl of spaghetti!

The pH of the pool is affected by nearly everything that is introduced to the water. The chlorine that is continually being pumped in to the water has an especially strong impact.  Depending on the type of chlorine being used, the pH of the water will begin to drift up or down. The balance between effective sanitation and bather comfort is found in the pH range of 7.2 to 7.8. In order to achieve this balance, some form of pH control is required. Otherwise the constant addition of chlorine will drive the pH of the water to extremes.

Traditionally pH has been controlled by hand. To start, the pool maintenance person first measures the water’s pH. Let’s say for this example that the pH is too high and needs to be reduced. He or she diligently calculates out the amount of acid to add, mixes the acid first with water so that it doesn’t depress the Total Alkalinity, and adds the mixture to the water. Is the job done? Not necessarily. Let’s look at what has just happened.

As soon as the acid mixture was added to the water the pH dropped like a stone. Once it bottomed out (probably at a lower level than was desired) the pH immediately began its journey back to the place that it was before the Acid addition. A couple hours later the pH is measured again, again found to be high and the process is repeated over and over like a roller coaster. Not only does this process make work for the maintenance personnel, it also affects the balance of the other critical chemical components of the water and makes the water less comfortable for bathers.

The solution to this roller coaster ride is a good chemistry controller.  Controllers have come a long way in the past few years, to the point where the entire pump room can be automated if desired. Commercial pools do not have to make a large investment into a full pH/ORP controller, although I advise all commercial bodies of water to consider this approach. pH only controllers are also available. With either option, a chemistry controller is mounted in, or near, the pump room and a pH sensor is installed in direct contact with the pool water. The sensor measures the pH of the water and relays the information to the controller, which monitors the reading. When the pH of the water creeps out of range, the controller activates an acid or base feed, depending on what is necessary, in timed bursts. This constant on/off method allows for instant correction of a pH shift, which therefore results in an evenly maintained pH reading throughout the entire day. Not only does pH automation drastically reduce the amount of time that maintenance personal must spend balancing the water daily, it also makes pH balance a safer activity, increases the overall chemical stability of the water, and makes the pool a consistently more pleasant place to swim.

Are you still managing your pH by hand? If so, don’t you think it’s time that your facility looks into pH automation? It is definitely one of the most important upgrades you can make.