Salt Water Pools Part 1October 10, 2016
Is Salt Water Bad For Your Swimming Pool?
Is salt water bad for your swimming pool? In a word, yes. This is information that most pool guys will not tell you. There are many different reasons that they might not tell you in clear terms like this why salt is bad for your pool. The most common reason is simply that they just don’t know any better. Also, if selling a salt water system to a customer any mention of damage to the pool as a result of salt would likely spoil the sale. In these cases the risks associated with salt water in pools is conveniently neglected during this conversation.
Sadly, there is also a wholesale lack of knowledgeable pool technicians within the industry. Of all the problems that can exist within a pool system, the problem of salt water being bad for your pool is probably the single most complicated one. In order to understand this problem your pool guy would need to have an advanced understanding of electrical theory, building standards and water chemistry and the reality is that most pool guys simply do not have these qualifications. Galvanic corrosion is the name of the electromechanical process that deteriorates your pool as a result of adding salt to it. If you want to make an informed decision about adding salt water to your pool then you need to learn as much as you can about this subject.
How Does Salt Water Damage Pools?
Galvanic corrosion is an electromechanical process where current will travel between two (different) metals within a galvanic couple. In simple terms, a swimming pool is just like a giant battery. To make a primary battery you would submerge differential metals within an electrolytic solution. An electrolytic solution is essentially water with salt in it…just like your pool. Since your pool is an electrolytic solution (since it has salt in it) and you also have differential metals within the system (such as galvanized steel, stainless steel, aluminum, titanium, brass and copper) then your pool actually becomes a giant battery.
The amount of current generated between metal components in a swimming pool is very small. It is not enough to feel shocks from the water, nor enough to be a concern for electrocution. The electric current generated is tiny. You could only detect this current with sensitive electronic testing equipment, or by virtue of seeing the damage as a result of this problem. The nature of the pool battery is such that the current being generated might be small, but it runs 24 hours per day, 7 days per week. The cumulative effect of this is a dramatically reduced service life for integral metal components of the pool.
The reality is that all swimming pools have this problem with galvanic corrosion if they use chlorine sanitizer. Chlorine is salt based so by adding chlorine to your pool you are actually adding salt. A salt water pool however has approximately ten times the salt level of a traditional chlorine pool. This is specifically significant since there is a linear increase in galvanic activity between 0 PPM salt all the way up to ocean water levels of 25,000 PPM of salt. If a salt water pool has ten times as much salt as a traditional chlorine pool then this means that the rate of galvanic corrosion also increases ten times when you switch to salt water. Doesn’t this sound like the kind of thing that someone should have mentioned to you when you asked about adding salt water to your pool? I sure think so, but even today you don’t need to look very far to find a pool guy boasting all about how “salt water pools are maintenance free” or “salt water is better than chlorine”. Salt water is not better than chlorine. Salt water is chlorine. Any person who tells you salt water is better than chlorine simply has no idea what they are talking about and fundamentally does not understand how salt water in swimming pools works.