pH correction
pH is arguably one of the most important parameters in water chemistry because it strongly influences the way in which chemicals react with each other. pH has the power to affect what chemicals the water contains, how the water behaves and the type of filtration necessary for effective treatment.
What is pH?
pH is a measure of the number of free hydrogen ions (H+) present in a substance, or more specifically, the number of free hydrogen ions relative to the number of free hydroxide ions (OH-). Hydrogen ions are acidic in nature whereas hydroxide ions are alkaline, so the balance of these ions will determine the overall acidity or basicity of a substance.
The pH scale
On the pH scale which ranges from 0 to 14, pure water sits in the middle at 7 because the hydrogen ions and hydroxide ions are perfectly balanced, resulting in a neutral pH. Any pH less than 7 is classified as acidic and any pH higher than 7 is classified as basic.
How do you know if you’ve got a problem with pH?
Usually, a pH problem is identified when the water test fails, with the pH sitting outside the regulatory parameters of pH 6.5 to 9.5. But, there are several noticeable indicators that are symptomatic of a pH problem.
The indicators of a pH problem
Corrosion
Acidic water has corrosive properties that can cause metals to dissolve over time. The more acidic the water, the more aggressive (and damaging) the corrosivity. Metal elements within the water distribution system can include pipework, tanks, tank linings, plumbing fixtures and pumps.
The consequences of dissolved metal entering your water supply will depend on the type and amount of metal present, however the consumption of elevated concentrations of metals can be harmful to health, especially if the levels exceed the regulatory limits. A metal such as lead is particularly concerning due to its established health risks and lack of warning signs.
Staining, sediment and a metallic taste
While pH independently doesn’t alter taste, odour or appearance, its dissolution of metals can have a significant impact on these characteristics.
Corrosion of copper often results in turquoise staining to plumbed appliances. It can also turn bleached hair green and give water a metallic taste. Alternatively, the corrosion of cast iron or steel pipes can leave orange/brown staining and sediment on sanitaryware and laundry, as well as imparting a metallic taste on the water.
Leaks and equipment failure
As acidic water starts to dissolve the metal elements within your water system, pinhole leaks can start to establish themselves throughout the network, while larger pieces of metal equipment may start to show signs of deteriorating performance or complete failure. Leaks are commonly observed with copper piping and dealing with these leaks can be expensive and irritating.
Avoiding these issues can include changing out metal components before leaks and perishment become a concern, or putting in preventative measures that address the root of the problem, such as reducing the corrosivity of the water with a pH corrector.
Are these signs sounding familiar?
Introducing the solution:
a pH corrector
How does a pH corrector work?
The unit
pH correction takes place using a pH corrector; a vessel containing specially formulated alkaline media which slowly dissolves into the water as it passes through the unit, consequently increasing the pH.
The process
The water enters the vessel through the inlet at the top of the unit, flows down through the media to the bottom of the vessel, and finally heads back up and out of the unit through the central riser tube.
The details
As with all system designs, the size of the unit and type(s) of media placed in the vessel will differ depending on parameters such as water quality, flow rate and usage demands, so we always recommend starting with a water test and designing a solution from there.
Need to get started with a water test?
What are the benefits of a pH corrector?
Damage prevention
The biggest asset of a pH corrector is prevention. Metal corrosion, pinhole leaks, colourful staining, equipment failure and declining water quality are all expensive problems to fix. Preventing them as soon as possible saves a lot of hassle later on. These vessels can even help to avoid the consumption of excessive concentrations of metals which can have significant health implications. This is particularly important when symptoms of some metal contaminants can go unnoticed, as is the case with lead.
Minimal maintenance
Since the media slowly dissolves into the water over time, the pH unit will require periodic media top-ups to maintain treatment efficiency. The exact frequency of these refills will depend on the water quality, average flow rate and overall design of your system. For new systems, projected maintenance needs are always discussed prior to installation. For existing systems, we can discuss your current set up and sort out what maintenance you need. After a few refill cycles, it is considered best practice to perform a full media removal and replacement, and internal clean of the vessel. This helps with prolonging equipment longevity and performance.
Built-in automation
The daily and weekly maintenance of pH correction units are handled by automatic control valves which are housed at the top of the units. The control valves are programmed during installation. If necessary, these settings can be easily altered, either with over-the-phone support or an on-site visit (usually any changes are made at the annual service). Automation ensures minimal downtime and a reliable water supply in periods of higher demand as the unit is set up to self-clean during times of low usage, such as the early hours of the morning.
The importance of the right pH
The right chemical reactions
pH strongly influences the reactions that can take place within the water, affecting both the chemical compounds created during reactions and the behaviour of the water as a result. In water treatment, pH is particularly important for chlorine disinfection as chlorine reactions can only occur when pH levels are between ~6.5 and 8, meaning microbiological disinfection will be ineffective outside of this pH range.
Equipment efficiency
Effective water treatment relies on certain chemical reactions taking place at certain points in the process, and for the majority of water filtration equipment there are specific conditions in which they work best. This includes a specified pH range in which it will perform optimally and consistently, so the right pH is crucial for the efficiency of the entire system.
Balanced results
Every water source will have a slight variation in ideal pH because of the unique composition of the water. Hardness, total dissolved solids and the type of contaminants present are just some of the factors that will vary depending on pH and will also be influenced by changes in pH. The pH has to be corrected inline with these other parameters to achieve the desired outcome.