Electrolysis and Corrosion in swimming pool

H

H26988

Member
Location
Redwood Valley Ca.
Occupation
Senior Maintenance Technician
Newly installed pool at a hotel is experiencing corrosion and rust issues with lights and metal hardware in pool.
Chemical levels of pool water tested couple times daily, all kept within desired range. Pool contractor is stating it
is being caused by electrolysis in the water caused by high voltage power lines that run underground from main service to hotel,
that are running near the pool.
Has anyone ever heard of this even being possible?
 
tom baker said:
Yes it is very common to blame electrical for any issue not related.
Well, not likely that’s the cause.
Click to expand...
The pool, spa, and all equipment is still under warranty and retention funds. The contractor is stating that this condition is not covered under their warranty. I'm trying to figure out how to electrically prove or disprove this/their theory. I would think 480V Lines running from transformer or main switches to Hotel would be in conduit. I'm really struggling with the whole electrical frequency theory affecting the pool water if the pool was built and bonded correctly.
 
When you have water and electricity, you will always have electrolysis. As an example ... when you have a sailboat, which has a metal keel, in a marina, were people are living aboard, you must install a zinc plate to prevent the keel from falling off !
 
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#1 - it helps to do your own generic pool test, borrow one. It doesnt matter if its a salt or chlorine system- you can always scoop a handful of water and smell it... if its strong, dont let your kids in it.

#2- are we talking both ladders, handrails and light trims corroding?

#3- the pool guy is not a "high volt" (?) passing underground specialist.

Sounds like a passing off obligation deal.
Satisfy your contract and be done.
 
What is the actual logical/scientific explanation for why these hypothetical high voltage (how high?) lines running within so many feet of the pool underground would cause electrolysis, exactly?
It's on him to demonstrate that. I await your reporting back on his explanation...

Presuming the pool area was bonded properly, there's no reason adjacent lines should have any impact. Even if it wasn't, I'm struggling to see how it would occur.
 
NoahsArc said:
What is the actual logical/scientific explanation for why these hypothetical high voltage (how high?) lines running within so many feet of the pool underground would cause electrolysis, exactly?
It's on him to demonstrate that. I await your reporting back on his explanation...

Presuming the pool area was bonded properly, there's no reason adjacent lines should have any impact. Even if it wasn't, I'm struggling to see how it would occur.
Click to expand...
The reason is that you cannot prove it isn't, thereby shifting the blame to you.
Remember, you cannot prove a negative.

If you did not install the underground lines, why would it be your problem anyway?
 
Thank all that have replied and or commented!
I myself have been researching for the logical/scientific explanation for the electrolysis as presented by the contractor, including any input from this forum. NO LUCK SO FAR!
It is a problem/issue that I will inherit if not solved. The corrosion I'm speaking of is affecting both the handrails and metal light enclosures within the pool. I have rust leaching out onto the plaster. This pool and spa have been open for less than six months.
I am currently questioning proper bonding. I did find that every bonding wire clamp in the equipment room was installed incorrectly, and was loose. Could not be tightened down until I removed them and installed them correctly. With that condition I question all the bonding connections underground, within the concrete, and in the pool that I cannot get at. Unfortunately proper testing cannot be done with water in the pool, submerging all the parts in question that I can see.
The contractor did install sacrificial anodes in the light fixtures, but has since removed them and installed a anode inline in the equipment room.
I see no activity on that anode as of yet, it gets very little water flow and with the grounding issue I'm not surprised.
This will be a constant ongoing and costly problem long term if I cannot get it figured out.
I might add the contractor initially stated it was an issue that needed to be addressed by Pentair, the company that sold them all the pool equipment: including the lights.
I am now going to throw the ball back at the contractor for their response and or assistance, and see where that gets me. So far their only solution and or explanation is the underground wire scenario. I'm thinking they should have mentioned or addressed these things when installing the pool. The hotel was under construction at the same time and the electrical had already been installed.
I'll watch for any more insight from this forum, and will give any updates that come about.
 
This was an earlier thread on this subject:

https://forums.mikeholt.com/threads/electrolysis-in-a-swimming-pool.136986/

In general, it would take a DC current and not AC current to induce electrolysis. Of course metals with different electrochemical potentials can lead to electrolysis without having an externally applied current if they are electrically bonded together to complete a circuit, and they are both submersed in an electrolyte.

Are the lights in the pool low voltage DC, or are they AC?
Is this a salt water pool?
 
code compliance is only related to 680.11 and a reference that it cannot be under a pool or 5 ft horizontally from the pool perimeter. If compliant then the service wire not direct issue. The Pad mount and it's grounding electrode and NEV can become a factor, but not necessarily a violation. If all bonding done correctly then the NEV should not be a contributing factor for electrolysis. A Difference of potential related to bonding could be a possible factor. Another factor could be the equipment used not rated for the environment. Was original design for salt water vs chlorine based?

one article addressing:

Is Salt Water Bad For Your Swimming Pool? - CuLator Metal Eliminator and Stain Preventer for Pools and Spas

This is a wonderful article I came across. Please note, this information comes from Swimming Pool Steve: IS SALT WATER BAD FOR YOUR SWIMMING POOL? Contents of Steve’s article are below: Is Salt Water Bad For Your Swimming Pool? Is salt water bad for your swimming pool? In a word, yes. This is...
culator.com culator.com
 
H26988 said:
Newly installed pool at a hotel is experiencing corrosion and rust issues with lights and metal hardware in pool.
Chemical levels of pool water tested couple times daily, all kept within desired range. Pool contractor is stating it
is being caused by electrolysis in the water caused by high voltage power lines that run underground from main service to hotel,
that are running near the pool.
Has anyone ever heard of this even being possible?
Click to expand...
Yes. Read an article years ago about this. Residential pool having chemistry issues. Power lines ran underground between properties. I believe also there was a high Iron content present in the water and it was constantly green.
If I find it I'll post it.
 
If the pool is this new, are there copies of inspection reports and possibly even photos that could confirm proper pool bonding?
 
Are the metal parts in the pool rusting or are they becoming a bronze like color? I have seen the ladders and light rings that are Below the water line this bronze like color, the cause was that the Ph level of the water was so low that it was stripping the copper from the copper heat exchanger on the pool heater and plating it onto the grounded metal parts in the pool. When they say they are checking water quality several times a day, are they actually using a water test kit or are just looking at the digital readings on the pool control system? At the site I mentioned they told me the same story about daily testing, the pool water Ph was a about 3.4 when they actually tested it, seems there automatic system was not working correctly.
 
bgard said:
Are the metal parts in the pool rusting or are they becoming a bronze like color? I have seen the ladders and light rings that are Below the water line this bronze like color, the cause was that the Ph level of the water was so low that it was stripping the copper from the copper heat exchanger on the pool heater and plating it onto the grounded metal parts in the pool. When they say they are checking water quality several times a day, are they actually using a water test kit or are just looking at the digital readings on the pool control system? At the site I mentioned they told me the same story about daily testing, the pool water Ph was a about 3.4 when they actually tested it, seems there automatic system was not working correctly.
Click to expand...
Absolutely true.
I've heard the same statement over the years, "Yes, the water is fine. We tested it"
Commercial facilities across the country are required to record their findings at least every 2 hours. New facilities always have an automatic system to read and feed and record, but a physical test is still required.

The pH and the total alkalinity must not be allowed to fall into an acidic state which can damage everything the water makes contact with.
Low calcium hardness levels are also corrosive in a different way. High levels create scale on surfaces and can and have completely plugged up heat exchangers on pool heaters or boilers I have seen this many times..
 
H26988 said:
Newly installed pool at a hotel is experiencing corrosion and rust issues with lights and metal hardware in pool.
Chemical levels of pool water tested couple times daily, all kept within desired range. Pool contractor is stating it
is being caused by electrolysis in the water caused by high voltage power lines that run underground from main service to hotel,
that are running near the pool.
Has anyone ever heard of this even being possible?
Click to expand...
Was already mentioned once, but I agree and will mention again. Electrolysis comes from DC current. AC high voltage lines won't be an impact on that. Electrolysis can occur if there is dissimilar metals and an electrolyte between them - basic composition of a wet cell battery there and easy to do in a pool with right mix of metals and water chemistry.
 
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