Pool Corrosion Causes that you might have overlooked

Written By Timothy Te

19th January 2021

The constant exposure to moisture, chemicals, and sunlight is a perfect recipe for corrosion around your pool area! But aside from these typical culprits, there are actually some corrosion causes that you may not have thought about. Why is this important to know? Well, as the veritable 80’s cartoon said, “Knowing is half the battle”. And knowing about these causes can help us deal with it, rather than just chalking it down to, “oh, corrosion is normal around the pool.”

High Chlorine or Shocking your pool

Remember how high chlorine levels can kill off any pool contaminants and bacteria, but they can also do a number on plastics! While pool cleaning tools and equipment are made with treated materials to resist normal levels of pool chemicals, there’s nothing normal about the pool chlorine levels when you’re shocking the pool. So if you’re shocking the pool, take out your pool cleaners, pool toys, and anything else that’s made out of plastic from your pool.

Salt water chlorinators

The salt in the water itself is already a source of corrosion, there’s another type of corrosion that comes with using salt water chlorinators in our pools. This type of corrosion is called “galvanic corrosion”. Scientifically saying, galvanic corrosion occurs when dissimilar metals exist in a high TDS (Total Dissolved Solids) solution.

  • Dissimilar metals, check! Remember that the metals in your salt water cell is different from the metals in your pool fittings.
  • High TDS, check! Your salt water chlorinator needs a relatively high TDS (salt) level to work.
  • Metals must be in electrical contact, check! Your salt water chlorinator works through the process of electrolysis which involves, you’re right, electricity!

 

How do we prevent it? You can check Amazon or Ebay for a sacrificial zinc anode to draw in the galvanic corrosion effect. It’s main function for its existence is to get corroded first, hence the name “sacrificial” to protect the rest of your metal surfaces from galvanic corrosion.

To much / Too little sun

By now everyone knows that constant exposure to the sun’s UV rays can be a cause of corrosion to our pool equipment. Even if these are UV treated, it’s still susceptible to corrosion so if you’re not using your pool cleaners and other equipment, store them away from direct sunlight! A simple fix for a simple problem. This is also one of the reason why many "good" pool furniture isn't made from plastic, because the sunlight can do a number on them from constant exposure.

On the other hand, too little sun can also cause corrosion in our pools! How is this possible? Well, muggy weather leads to mold and mildew growth which can not only eat away at your surfaces but can cause health issues as well. While there’s nothing we can really do about preventing too little sun, we can prevent mold and mildew growth by periodically cleaning and scrubbing out dark and damp corners or even surfaces that usually get exposed to sun but are starting to show signs of mold growth.

Mulch in your garden

What does mulch have to do with corrosion in and around our pools? Well, if you’re the type that uses mulch in your yard to prevent weeds and to improve your soil’s structure and drainage then good on you! The downside to this is that mulch is basically concentrated phosphates and nitrates and if any of them blow into your pool, it’s like you’re placing algae food directly in your pool! So how do we combat this? We can do two things, either replace the mulch with something more stable like gravel, or you can keep the mulch and proactively dose your pool with phosphate remover, the choice is up to you!

Low Pool Chemical Levels

The three main pool chemical levels that we need to monitor to minimize corrosion in your pool. Well, we actually have to monitor all of our pool chemical levels but here are the top three that cause corrosion in our pool.

  • Low pH levels - low pH levels means that your water is acidic and acidic water basically eats away at your pool surfaces. To prevent this? Keep your pH levels in check by testing your pool water regularly and raise the pH levels accordingly. On top of that, the lower your pH levels, the more effective (and corrosive) your chlorine will be! Read more about the relationship of pH levels and chlorine here.
  • Low Total Alkalinity levels - this is somewhat related to the low pH level problem. A low total alkalinity will lead to wild pH swings, meaning you’ll get the problem of both having low pH and high pH in short amounts of time, and that’s no fun!

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  • Low calcium levels - As we covered in some of our previous blogs, water will always to to reach a state of equilibrium when it comes to calcium levels. A low calcium level will mean that water will actively seek calcium to normalize its levels and the only way they can do that is “eat” the calcium from your pool surfaces. The way to prevent this? Test your calcium levels and apply some calcium up if you find that your calcium levels are lower than where they’re supposed to be.

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Conclusion

When it comes to corrosion in and outside of our pools, we don't have to just sit back and accept it as a part of pool ownership. By identifying the other causes of corrosion, we can actively address these to reduce the amount of corrosion that's occuring in our pool areas.

Do you have any questions about this topic or the featured products? No worries, we're here to help! Drop us a question down below and we'll get back to you ASAP.

Happy swimming :)

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Written By

Timothy Te

Pool Guru at Mr Pool Man

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