More on Corrosion and Salt Systems

An letter to the editor of the Service Industry News: It was good to come across your article, basically asking the market for more informed feedback as to the question “Do chlorine generators cause corrosion?”

There is no real link to the article, and it may be replaced but for now http://www.serviceindustrynews.net/letters-to-the-editor/

By Timothy S Petsch TMI Corporation, Some of the points that we have also been promoting:

  • Corrosion — In and within the water and pool equipment.  This is where the finger of guilt has been firmly pointed at salt, and it is just not correct. I have seen corrosion in many a non-salt pool, and the cause of the corrosion is the same for traditional chlorine pools, especially liquid chlorine.
  • So what is going on here? Well, quite simply it is an issue of lack of, and/or improper bonding of metallic pool equipment. The National Electric Code requires bonding as part of their Rule 680.26, but it seems that many professionals do not know the difference between grounding and bonding. And while they take great care to ground all electrical equipment, bonding is, in many instances, ignored. Bonding lugs are provided on all mechanical equipment in pump rooms for a reason. If the bonding is not correctly installed, or not tied into an “Equi- Potential Bonding Loop”, and not terminated correctly, then the addition of salt into the water creates a battery-like situation. The conductive ions, or salt particles, then provide a path for the current flow, mVDC, to ground itself to a metal pool component, beginning the corrosion process.
  • In contrast if liquid chlorine is the sanitizer of choice, then for every gallon of chlorine added, approximately 2- to 3- pounds of salt is formed, raising the salt level in the water, sometimes getting to levels that can be comparable to that of a salt pool.

To date, we at ControlOMatic have only come across a few spas that have experienced some damage and it has always been to low water hardness or excessive chlorine levels because of an improperly setup salt system, and only 1 of those we were not able to explain which this article does. In that one case they did replace the heater before our system and we did send them a sacrificial anode to test and have not heard back.

2 Comments

  • Erik

    Reply Reply July 11, 2016

    I have a Hot Tub installed on my deck and hard wired to a service panel. I believe adding a ground rod to this installation would violate the NEC in my area. Grounding should only occur at the main service panel. My hot tub is grounded to the main service panel and all metallic components in the pump compartment are bonded together (but I would have to check if that bond is also grounded). Will not having this ground rod create a corrosive environment for my hot tub when using salt water? I would like to try your system but I am worried about corrosion taking out the heater.

    • admin

      Reply Reply August 24, 2016

      Good question. You should follow the laws for your area, if a ground rod is required for the spa make sure to put one in. We have a ground rod on our spa with no problems to any of the spa equipment. Make sure the hardness is between 200 to 400 and the chlorine level is consistent around 2 PPM. You can always add a zinc sacrificial anode, if you search for it there is a lot of choices and tips.

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