new swg pool do i need zincs?

[house]

Just curious my new pool is in the plumbing phase and I am curious if i Need a zinc anode to stop my heater/pump/whatever other metal is in the water from being eaten up? Am i just being paranoid or is this something i really need? I am looking at getting an anode that goes in a PVC to and has a bonding lug on it, is this what most people use, or do i not even need it?

Thanks

Nick

 

[tim5055]

Nope, no anode needed. Just keep the pool balanced and you should be good to go.

 

[house]

http://www.swimmingpool.com/blog/risks-salt-water-pools-every-pool-owner-needs-know

I found this article while searching, galvanic corrosion is not an issue of chemicals in the pool, more like stray electric current going through water that has salt in solution. I have seen this happen to copper pipes that are in contact with galvanized steel. I was under the impression this is why bonding is done in the pool and attached equiptment

 

[tim5055]

Bonding and galvanic corrosion are two separate issues. Unless it is a seasonal/temporary pool then bonding is required.

 

[BobbyR]

My next door neighbour just had the liner replaced on their rectangular, inground pool, built in 2007. The pool has used a SWG since it was built. The steel walls of the pool were rusted top to bottom all around and had to be sanded and filled and smoothed out with some white substance (bondo?) before the new liner was installed. The folks installing the liner were the same people who built the pool and they said that they are seeing this with many of the SWG pools they have built when it comes time for a new liner. He told my neighbour that the new liner will outlast the walls and that the pool will have to be re-built sometime in the next 6 to 10 years. They installed a sacrificial anode but wouldn't guarantee that it will help to prevent further corrosion. This is just one data point but it does seem to confirm the concerns regarding salt induced corrosion of steel components in SWG pools. He said they advise new customers now of the problem when they install a SWG system so they are aware and can decide accordingly.

 

[Donny]

I would bet those harsh winter months did more damage than the salt in the pool. If the salt did that damage to the steel walls of the pool, what did it do to every piece of metal in the pool ??? Ladders, lights etc ??? Couldn't disagree more with SWG causing damage to the steel walls.

 

[BobbyR]

Cold weather corrosion of automobiles is associated with salt on the roads, not the cold per se and, as far as I know, there's no long term history of excessive corrosion of pool walls in colder climates. As for the rest of the metal parts in the pool, they may have been damaged as well. I can't comment as I was only looking at the walls. In any case, I'm simply reporting what I saw and what the pool builder told me. According to him this is a recent development, appearing in the earliest salt water pools in this area which are around 10 years old now. What possible reason would he have for saying such a thing if it wasn't what he was actually seeing? Frankly, it looks pretty conclusive to me.

 

[tim5055]

What possible reason would he have for saying such a thing if it wasn't what he was actually seeing? Frankly, it looks pretty conclusive to me.

Post hoc ergo propter hoc

Just because it is a salt pool and it is rusted does not necessarily support the conclusion that salt caused the rust. I'm not saying it didn't, but that conclusion can't be reached with the data at hand.

Post hoc ergo propter hoc - Wikipedia, the free encyclopedia

 

[BobbyR]

Well, supported or not, that is the conclusion that the pool's builder has reached and, I have to say, it's easy to see why after looking at the damage. Anyway, I have no axe to grind here. I just thought it would be of interest to the OP.

 

[tim5055]

Well, supported or not, that is the conclusion that the pool's builder has reached and, I have to say, it's easy to see why after looking at the damage. Anyway, I have no axe to grind here. I just thought it would be of interest to the OP.

understood, but sit and read a sufficient number of threads and you will find that there is a large number of builders who for wahever reason are against SWCG pools, no matter what the construction. We have had folks showing up saying his builder refused to install one because it can damage the plaster. I trust what builders say at about the same level,as I trust pool stores. When builders talk about pool chemistry their credibility goes down in my book.

 

[JoyfulNoise]

Well, supported or not, that is the conclusion that the pool's builder has reached and, I have to say, it's easy to see why after looking at the damage. Anyway, I have no axe to grind here. I just thought it would be of interest to the OP.

I agree with @tim5055, you need to take what pool builders say with a grain of salt (haha, pun definitely intended!!). No steel structure buried in the ground is going to be corrosion free and the significant degree of corrosion you described is more likely the fault of the original PB uses a substandard grade of steel and improper bonding than the fault of the salt water chlorine cell. See THIS ARTCLE for a good primer on how stainless steels corrode in soils and concrete. There are also grades of steel that are DESIGNED to corrode a bit so that they form passive oxide layer that then becomes a barrier to further degradation. In those cases, using an angle-grinder to remove all of the "rust" and then re-coating it with Bond-O is exactly the WRONG thing to do.

To the OP - there is an article in PoolSchool on proper bonding and grounding and the differences between them. As long as your PB is ensuring that all of your equipment is properly bonded and appropriately grounded, then the increased salt levels will not cause you issue. The bigger problem is that many PB's don't understand the Do's and Don'ts of material compatibility with salt water (like not using cheap aluminum fasteners with salt water).

 

[BobbyR]

I think the steel panels used were galvanized structural steel, not stainless. Pretty standard kit. I didn't know that stainless was even an option for pool walls but these certainly didn't look like it. Unlike stainless, rust on ordinary steel does not form a passive layer or provide any protection to the underlying metal. It also has a rough surface so I can understand why they would sand it down and patch it. As for improper bonding, that could certainly cause a problem. I have no idea if that was done properly or at all. Maybe that's the issue here. That said, this isn't a fly by night builder. They've been around a long time and build a pretty nice pool. My neighbours on each side both have the same pool, large rectangular with straight edges and sharp corners. Beautiful pools.

 

[Donny]

I agree with @tim5055, you need to take what pool builders say with a grain of salt (haha, pun definitely intended!!). No steel structure buried in the ground is going to be corrosion free and the significant degree of corrosion you described is more likely the fault of the original PB uses a substandard grade of steel and improper bonding than the fault of the salt water chlorine cell. See THIS ARTCLE for a good primer on how stainless steels corrode in soils and concrete. There are also grades of steel that are DESIGNED to corrode a bit so that they form passive oxide layer that then becomes a barrier to further degradation. In those cases, using an angle-grinder to remove all of the "rust" and then re-coating it with Bond-O is exactly the WRONG thing to do.

To the OP - there is an article in PoolSchool on proper bonding and grounding and the differences between them. As long as your PB is ensuring that all of your equipment is properly bonded and appropriately grounded, then the increased salt levels will not cause you issue. The bigger problem is that many PB's don't understand the Do's and Don'ts of material compatibility with salt water (like not using cheap aluminum fasteners with salt water).

Absolutely agree with this statement.

 

[JoyfulNoise]

Absolutely agree with this statement.

I don't doubt that the PB's doing steel pools are doing good work. I think this all comes down to a problem of PB's, once established in their trade, get into the pattern of "knowing what they know" and not updating their practices with the changing times. I'm not convinced either way that salt water pools are the problem but that doesn't mean they aren't problematic. I would think that with a salt water pool, you'd want to consider a change in materials like using galvanized steel that has an additional conversion coating on it (trivalent chromium conversion coating is one example) or, if available, stainless steel (I have seen it as an option in some areas). The problem is, any changes in materials made are likely to drive up the cost of the build and a PB might not want to work with different materials, might not be able to eat the cost or not want to pass that cost on to a customer as it could potentially reduce business.

In my area, many PB's will ask customers to sign releases from their standard warranties on specific aspects of the build if they decide to use a stone material that the builder feels will not hold up to salt water exposure (e.g., soft stones like limestone, etc). I wonder if the steel PB's do the same - if you want a salt water pool, then you only get a 10 year warranty on structural failures and no coverage for rust damage.

 

[Donny]

I have a Limited Lifetime Warranty on my steel walls. I would like to add, if a PB in my area has not grounded and properly bonded the pool, they will fail inspection.