After 3 weeks.... corrosion!!!

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BIC

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Jul 7, 2007
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I will try to make my story very short.

- I got a brand new pool installed 3 WEEKS ago
- The pool is an 24' AG with vinyl liner
- I also have installed the SWG Aquatrol (from GOLDLINE/Hayward)
- Since the pool is installed, I have been analyzing my water everyday and succeded to get a a good balanced water
- Today (after only 3 weeks) I noticed that my 4 bolts at the bottom (in the water) of the ladder are starting to rust (corrosion). When I rub the bolts (under water) I can see corrosion dust coming out of it.
- I then looked at my skimmer, the bolts are starting to corrode too, it's just a little bit, but I can see that it's starting.
- I went to a pool store where they sale the Aquatrol and asked about the corrosion I have (don't ask me why I didn't go to the store that sold me the pool). They asked me if my pool was grounded, I said "NO", but the Aquatrol is grounded (not the pool). There is a big copper wire attached to the aquatrol and the other end is attached to a 4 feet metal bar that they (pool builder) put into the ground.
- The pool has not been grounded because the pool store, that sold me my pool and the SWG, said that a resin pool DO NOT HAVE TO BE GROUNDED. Everything, execpt the the screws in the posts/skimmer and the wall, are resin. They said that even if the pool is in resin, the metal wall requires that the pool must be grounded.
I don't know what to think now. I read many things about SWG and corrosion, but I was never expecting a so QUICK (3 weeks) corrosion problem.

My questions:
- Is it true that a resin pool, with a metal wall, has to be grounded when you use a SWG?
- Is it true that if I ground my pool, the corrosion will STOP?

I'm starting to be very nervous about that problem.

BIC
 
First thing that would be helpful is to post a full set of test results for your water. Just saying that you have balanced water doesn't really tell us anything.
Improper water chemistry can cause corrosion very quickly, SWG or not.
Are you sure it's corrosion and not scale deposit you are seeing?
More info would be very helpful.
 
waterbear said:
First thing that would be helpful is to post a full set of test results for your water. Just saying that you have balanced water doesn't really tell us anything.
Improper water chemistry can cause corrosion very quickly, SWG or not.
Are you sure it's corrosion and not scale deposit you are seeing?
More info would be very helpful.
Click to expand...

My last water test (today):

PH: 7.5
FC: 4
Stabilizer: 30
Total Alkakinity: 100
Calcium (hardness): 175

The Pool Store said everything is ok.


What is the difference between corrosion and scale deposit?

I also see reddish sand in the bottom of the pool.

Waterbar,

Could you tell me if a resin pool should be grounded when using a SWG? Does it make sens or not?
 
Strannik said:
my bet would be that bolts are not suitable for salt water...
there is no practical way to ground them anyway, so they would rust even if your pool was grounded
Click to expand...

Well, it is not very commun to have rust on the skimmer bolts after 3 weeks. I'm trying to explain that fact. The store said it is because my pool is not grounded. They say that the electrolys (SWG cell) would make anything metal touching the water corroding :?. I'm not an expert, but they also said that Hayward told them that when they got the Aquatrol training.
 
well, I can tell you first off the bat that your water is NOT correct for a SWG. Goldline recommends 60-80 ppm CYA and you only have 30 ppm. What is your salt level?

based on the test results you posted and assuming a salt level of 3200 ppm and a temperature of 78 degrees your water is slightly on the corrosive side and it has nothing to do with the SWG but rather the water balance. (to be fair it is really more of a problem for plaster pools and not necessisarly indictive of metal corrosoin but is does illustrante that your water IS out of balance and not set up properly for the operation of your SWG. It would not be fair to say that the corrosion you are experiencing is because of the SWG and I doubt that grounding has any effect on it.

My suggestion would be to replace the bolts in question with stainless steel ones since it seems that the ones you have are not.
REddish sand in the bottom of the pool could be iron. It could be coming from your fill water or it could be coming from the bolts if they are rusting. If therer is iron in your water chlorine can cause it to precipitate out as rust, whether you have a salt pool or a manually chlorinated pool. There really are too many possible causes to say that your problems are caused by the salt system. It is a possiblility but I would get your water balanced properly first.
The fact that your pool store told you your water was in balance but you only have 30 ppm CYA in the water tell me that your pool store does not have a great deal of knowedge about operating a salt pool!
 
True, but to ground the bolts if they don't make metal to metal contact with something more solid, you would need to run a separate wire to every bolt.

And if Hayward's chlorinators make everything metal corrode then there is something seriously wrong with their product and i would stay away from it. More likely, the person at Hayward didn't know what they are talking about, or there was some kind of misunderstanding somewhere along the way.

Anyway, if you get reddish sand on a bottom of a pool, it's unlikely to be corrosion. Most likely it's some metal salts (like iron), depositing on your bolts and pool bottom.

waterbear would answer this better, as i'm not a chemist :)
 
waterbear said:
well, I can tell you first off the bat that your water is NOT correct for a SWG. Goldline recommends 60-80 ppm CYA and you only have 30 ppm. What is your salt level?

based on the test results you posted and assuming a salt level of 3200 ppm and a temperature of 78 degrees your water is slightly on the corrosive side and it has nothing to do with the SWG but rather the water balance. (to be fair it is really more of a problem for plaster pools and not necessisarly indictive of metal corrosoin but is does illustrante that your water IS out of balance and not set up properly for the operation of your SWG. It would not be fair to say that the corrosion you are experiencing is because of the SWG and I doubt that grounding has any effect on it.

My suggestion would be to replace the bolts in question with stainless steel ones since it seems that the ones you have are not.
REddish sand in the bottom of the pool could be iron. It could be coming from your fill water or it could be coming from the bolts if they are rusting. If therer is iron in your water chlorine can cause it to precipitate out as rust, whether you have a salt pool or a manually chlorinated pool. There really are too many possible causes to say that your problems are caused by the salt system. It is a possiblility but I would get your water balanced properly first.
The fact that your pool store told you your water was in balance but you only have 30 ppm CYA in the water tell me that your pool store does not have a great deal of knowedge about operating a salt pool!
Click to expand...

I told them (pool store) about my stabilizer being at only 30, but they said it's ok, we are at the end of the season. They didn't want me to have a chlorine problem if the stabbilizer gets to high. Even in my post here:

http://www.troublefreepool.com/viewtopic.php?t=1898

people kind of said don't add more stabilizer :?..... I'm lost.

My salt level is 3100ppm (Aquatrol reading), the pool store says 2500 ppm, but I don't belive that. I put 7.5 bags (20KG each).

So your recommendation is to ADD stabilizer and get it to 60 ppm. I don't think it will help on the corrosion problem, but I can do that easely.

You are aslo saying that grounding the pool will not help to stop the corrosion.

What else should I do?
 
If you do end up replacing the bolts with stainless steel, save some of them. Then you can do some experiments with different levels of salt water (with chlorine in them as well as CYA) to see if it's just the saltier water that makes the difference as I suspect it is (i.e. it's not the SWG itself). That would help us prove what we believe is going on as all metal corrosion so far reported has been attributed by various people as having to do with electrolysis with the SWG even though such parts aren't always electrically connected (as in your case) -- if we can prove it's the salt level and not the SWG itself, then that implies a different sort of protection required.
 
chem geek said:
If you do end up replacing the bolts with stainless steel, save some of them. Then you can do some experiments with different levels of salt water (with chlorine in them as well as CYA) to see if it's just the saltier water that makes the difference as I suspect it is (i.e. it's not the SWG itself). That would help us prove what we believe is going on as all metal corrosion so far reported has been attributed by various people as having to do with electrolysis with the SWG even though such parts aren't always electrically connected (as in your case) -- if we can prove it's the salt level and not the SWG itself, then that implies a different sort of protection required.
Click to expand...

I really don't know if the corrosion problem is because of the salt (only) or is it because of the electrolysis done by the SWG. The problem is: you can have in your pool the salt only (without the SWG), but you cannot have only the SWG (you need the 3000 ppm of salt).

Do you belive that I should ground my pool? (original question)
 

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Grounding isn't really what you want to do. Grounding just the ladders could cause a problem if the SWG failed in an unfortunate way. All of the metal parts that touch the water could be connected together, so that all of the metal parts are at the same electrical potential. This is called bonding and is somewhat different from grounding. This is required for in ground pools but isn't usually needed for above ground pools. The SWG should have a bonding terminal on it somewhere.

But I don't think that that is the problem and thus doubt that bonding everything would actually help. I suspect that your bolts are simply made of inferior materials.
 
I'm no expert in any of this, but we have had salt in our AG pools for 2 years now and only had the SWG for a while (we did the SW without SWGen thing - see PF posts and early TFP posts for that) - Anyway, we have had NO problems with corroding bolts or anything. I do know that all our hardware was SSteel. The only thing that showed any problems with the head of the standard poolbrush with a bit of pitting. All the screws and bolts are good yet.
 
JasonLion said:
Grounding isn't really what you want to do. Grounding just the ladders could cause a problem if the SWG failed in an unfortunate way. All of the metal parts that touch the water could be connected together, so that all of the metal parts are at the same electrical potential. This is called bonding and is somewhat different from grounding. This is required for in ground pools but isn't usually needed for above ground pools. The SWG should have a bonding terminal on it somewhere.

But I don't think that that is the problem and thus doubt that bonding everything would actually help. I suspect that your bolts are simply made of inferior materials.
Click to expand...

I would tend to agree with Jason as well. I added a SWG this year, and found that the screws that I used to attach the top part of my ladder to the base (and which stay underwater) started rusting within two weeks. I went to Lowe's and bought some stainless steel screws, replaced the corroded ones, and haven't had a problem since.
 
MikeInTN said:
JasonLion said:
Grounding isn't really what you want to do. Grounding just the ladders could cause a problem if the SWG failed in an unfortunate way. All of the metal parts that touch the water could be connected together, so that all of the metal parts are at the same electrical potential. This is called bonding and is somewhat different from grounding. This is required for in ground pools but isn't usually needed for above ground pools. The SWG should have a bonding terminal on it somewhere.

But I don't think that that is the problem and thus doubt that bonding everything would actually help. I suspect that your bolts are simply made of inferior materials.
Click to expand...

I would tend to agree with Jason as well. I added a SWG this year, and found that the screws that I used to attach the top part of my ladder to the base (and which stay underwater) started rusting within two weeks. I went to Lowe's and bought some stainless steel screws, replaced the corroded ones, and haven't had a problem since.
Click to expand...

Hi MikeInTN,

What about your skimmer screws? Were they rusted too?
 
BIC said:
[quote="MikeInTN
I would tend to agree with Jason as well. I added a SWG this year, and found that the screws that I used to attach the top part of my ladder to the base (and which stay underwater) started rusting within two weeks. I went to Lowe's and bought some stainless steel screws, replaced the corroded ones, and haven't had a problem since.
Click to expand...

Hi MikeInTN,

What about your skimmer screws? Were they rusted too?[/quote]

Hey BIC,

No sir, they were not, and are not.
 
Here are my ladder screws after exactly 6 days. The brand new ladder was instaled 6 days ago:

http://img158.imageshack.us/img158/9387/img3208xb4.jpg

http://img158.imageshack.us/img158/1431/img3207sm3.jpg

http://img158.imageshack.us/img158/9034/img3206ds6.jpg

http://img158.imageshack.us/img158/4065/img3205zz7.jpg

I'm posting the pictures because I wanted to give everyone a look at the type (level) of rust I was talking about.

I'm going tonight to get new stainless steel screws and see what will happen to them.

BIC
 
I vote that those are not SS either. Even with stainless, each bolt/screw varies. I have 1 (one) screw on my skimmer face (out of probably 16 to 20) that has a slight bit of rust after 3 years of salt/SWG. On my ladder, I had to replace 2 nuts that were clearly not stainless even though ALL the rest of the nuts and bolts were.

I think this is a clear example of Occam's razor! The most simple answer is probably correct.
 

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