Rebar rust through pool plaster caused by bad water chemistry?

[Slange]

Hello - one of my first posts, so go easy on me

My pool is ~5 years old, regular chlorine pool, and regular white plaster. About 3 weeks ago I noticed a rust spot that my pool guy said would not come off despite his tricks (i.e., vitamin c, little sandpaper, etc.). So I called the pool company that built the pool, and they sent out the company that plastered the pool. The plaster company said that improper water chemistry had caused the plaster to thin, which allowed water into the gunite (which is porous) that rusted the rebar. Then the rust came to the surface. The rest of the pool looks amazing to me, with no other trouble spots.

I'm clueless about this, so wanted to get your thoughts on water chemistry causing this problem. In my research, it seems these issues are caused by rebar poking through the gunite, or the plaster being too thin. Attached are some pics, which are after the plaster folks dug away some of the plaster. The circle spot is about the size of a quarter. I really don't want to spend the ~$1000 to patch the spot, or completely redo the plaster.

Is this caused by improper water chemistry? Is it normal for plaster to fail after 5 years? Any insights would be appreciated. Thanks.

 

[JamesW]

Probably not a water chemistry problem.

Probably a rebar or wire tie that was too close to the top of the gunite and a thin plaster spot.

What are your chemistry readings from startup to today?

I would probably just scrape the spot off with a sharp wood chisel and then cover the spot with white epoxy putty or underwater pool patch.

It will eventually bleed through again and you will need to redo the patch.

You can drain the pool, cut out the spot and then patch, but that's a lot of work and probably not worthwhile.

 

[Bama Rambler]

I'm sure others will chime in, but rebar rust through is caused by one thing, The rebar not being embedded in the concrete deep enough. Of course builders want to blame it on chemistry, but that's not the cause.

 

[Slange]

Thanks for your reply. I don't know the chemistry reading, but I have a trusted pool service company that has serviced the pool every week from startup. I'm really hoping I don't have to connect the two companies to get in an argument, as it likely won't go anywhere.

That is great news about just covering with epoxy putty. Is there a risk that the rust will spread under the plaster if it isn't cut out? I plan to get pebbletec installed in about 4-5 more years.

 

[JamesW]

Once rebar begins to rust, it will swell up and spread some depending on how much water gets to the metal.

It will eventually bleed through again.

I think that I would patch until you're ready to replaster and then cut it out.

 

[mknauss]

Welcome to the forum!

TFPC advocates pool owner management of water chemistry. Not knowing your pool water chemistry and relying on a once a week pool service lends itself to poor water chemistry management and high costs.

I suggest you read Trouble Free Pool and consider reviewing the entire Trouble Free Pool School book.

 

[ajw22]

BTDT, I had a similar problem except my plaster was 17 years old. Drained the pool, cut out the rusting rebar, cement patched the hold, and then did a full replaster of the pool.

If you are looking to hold someone responsible, fuggetaboutit. You already see the finger pointing. You don’t have enough evidence to pin tne rpoblem on one company.

I used the PB who did my pool to the repair. They just said the rebar was a bit to high in that area. We didn’t argue about it. They gave me a fair price to replaster and we moved on.

See what your PB will negotiate with you.