Thinking of a Salt Water Pool - Think Again!
Why we don't recommend salt systems
While homeowners naturally want beautiful and durable finishes in their pools, the look and durability of a good pool finish is highly dependent on its environment. Getting 20 to 25 years of use out of a pool finish requires diligent monitoring and proper water balance. That, of course, applies to any pool with any sanitation option.
Let’s take in the following:
The reality of Salt Pools is that they are actually chlorine pools – yes, salt is sodium chloride.
Cementatious (high-strength mortar) pool finishes are thin (¾” to 1” thick) coatings applied to the Shotcrete/Gunite shell of the pool.
The pool finish is not structural, nor is it a waterproof agent. And it is critical that proper technical practices in water chemistry be maintained to ensure the look and longevity of a pool finish as it is under water 24/7/365.
While maintaining balanced pool water is not always easy, pool professionals do have an ally to turn to - the Langelier Saturation Index (LSI). This index determines water balance based on readings of pH, total alkalinity, calcium hardness, and water temperature. This tool is not new to the industry, but it may be underused.
When dealing with pools with salt chlorine generators, it's critical to use the LSI because it accounts for the difference in total dissolved solids in the water.
I know it’s getting complicated right?
Take a pool that has a salt cell - we’re adding to the equation a piece of electronic equipment that needs regular checking to ensure that it is working properly and that it’s generating the correct amount of chlorine.
There’s MORE... usually salt pools have higher salt content than fresh water pools and the only way to remove salt from water is by dilution or draining to lower the salt level to safe standards. Understand that pool water that is not well-balanced with high salt content typically means higher calcium carbonate solubility. The pool's appetite for calcium is actually greater because water will balance itself, taking what it needs from the cement surface. This will prematurely damage the pool finish by making it rough. “Aggressive water” will also make the plaster penetrable by other elements like algae that may stain what was a pristine pool finish.
Now that’s on the surface. BUT there’s also the long-term structural damage that salt will have. As the cementitious surface deterioration slowly occurs - a more SERIOUS damage is happening below. While salt gradually erodes the plaster finish it then begins to penetrate the pool’s concrete shell and eventually the steel within. In that case, we’re no longer talking about simply re-plastering the pool, but something that can be much more expensive.
While there is an ongoing debate among some pool builders, plaster professionals and equipment manufacturers about this, the fact is that the NPC (National Plaster Council), the ACI (American Concrete Institute) that sets the industry’s standards for structural concrete, and several other organizations have adopted measures to avoid the use of salt in pools.
In my own experience and most of my colleagues agree that “Salt Systems” were a great selling tool with the skin benefits but after years of systems installed I’m no longer impressed. I have seen first hand what salt does after 10 or 20 years of salt misuse and I do not recommend ANY type of salt generators period.
My closing argument is....Salt is CORROSIVE, so why would you knowingly add salt to a pool after all we have learned? That is why we do not recommend or install salt systems as a water sanitation option anymore.
The good news is that there are MUCH better alternatives that have been around for decades.
See my Ozone Blog for details.
(Data for this blog has been gathered from different sources and reflects opinions of professional colleagues in the pool industry.)
SWD, International Watershape Institute