Pool and Spa Corrosion – An Atomic Point Of View

Today, corrosion is one of the most common problems faced by a majority of individuals. Statistical reports show that corrosion caused damages worth one trillion in 2016. In particular, the majority of swimming pools and spas are prone to corrosion. And the effects of this are damaging and often lead to significant pool repair costs. Fortunately, there are several techniques pool owners and contractors can implement to reduce pool and spa corrosion. But typically, as a pool owner, you need to understand the term corrosion at an in-depth level. This way, you’ll be able to help your customers prevent and treat this problem.

Foundational knowledge – The basic atomic model

Do you remember the term atoms in your science or chemistry class? Let’s rewind our knowledge a little bit. Usually, all materials consist of atoms. And a material that has one type of atom is an element. Every element has its atomic number. In the middle of the atom is the nucleus. The nucleus has both protons and neutrons. Also, electrons encompass the nucleus. Typically, electrons carry a negative charge. On the other hand, Protons always have a positive charge.

So how is all this information related to pool and spa corrosion?

Usually, electron number will dictate the corrosion reaction. For example, Sodium always loses electrons, hence becoming a positively charged ion or a proton. Conversely, chlorine tends to gain electrons. Such elements steal electrons from other elements. Therefore, they are known as negative ions. When positive and negative ions combine, they become insoluble solids. And this is why rust is often left behind once pool and spa corrosion has occurred.

What are the main ingredients for corrosion?

Generally, certain factors have to be present for corrosion to take place. Below are all the ingredients needed for corrosion.

• A cathode is responsible for gaining electrons. It is the oxidizer during corrosion. A good example is oxygen; Oxygen steals electrons from the metal in the pool equipment hence causes pool and spa corrosion.
• An anode is Responsible for losing electrons. It is the element that gets oxidized. In our case, this could be the metal used to make the pool equipment. It loses electrons to the cathode.
• An electrolyte: Electrolytes exist in liquid form. So, in our case, this is the pool water. Often saltwater is an exemplary conductor. Thus, it tends to be very corrosive. Note that the more the liquid dissolves materials, the more corrosive it becomes. That’s why salt water is more corrosive than normal pool water.
• The electrical contact of the cathode and anode. Typically, there has to be an electric path for the electric circuit to become complete.

So, if you want to reduce or prevent pool and spa corrosion, you must eliminate one of these factors. Of course, you cannot get rid of some of the factors mentioned above in most instances. Thus, you would have to identify creative ways of how to prevent corrosion.

How does corrosion in swimming pools and spas occur?

First, note that corrosion is an electrochemical reaction. Corrosion occurs when the metal (material of the pool equipment) loses electrons to another element (e.g., oxygen) found in the electrolyte (pool water). When this happens, a corrosion cell gets formed. Note that the quantity of material lost to corrosion matches the corrosion current. On the flip side, the corrosion current is indirectly proportional to the cell’s resistance and directly proportional to the cell voltage.

So, if you increase the cell’s resistance, you will reduce the rate of pool and spa corrosion. A real-life illustration is a pool heat exchanger experiencing a buildup of calcium carbonate deposits. In case you continue having unbalanced water chemistry, the heat exchanger gets more and more vulnerable to coating, especially on its inner diameter. And when there is a partial coating, some parts of the heat exchanger are generally more susceptible than others. Consequently, the section beneath the coating will be anodic, and the one outside the coating will be the cathode.

How do you prevent pool and spa corrosion?

If you have any metal equipment, corrosion should not come as a surprise to you. Corrosion occurs even on stainless steel. And it’s almost close to impossible to stop corrosion from ever happening on a metal. As a result, the techniques for preventing corrosion are often meant to slow down the reaction to 0%.

This method usually works pretty well only if done correctly. In fact, when you use the right techniques, you may not have to deal with corrosion for decades. As a pool owner, it would be best to identify the best practices that would help you prevent pool and spa corrosion. This way, you won’t have to deal with the massive costs that come with pool equipment repairs and replacements. Besides, you’ll prolong the durability of your pool.

it is clear that pool and spa corrosion is an electrochemical reaction. Understanding how corrosion works will help you find the best techniques for mitigating this problem.