Rust colored spots

[cheezedawg]

I've noticed a couple of small rust-looking spots in the shallow end of the pool. The pool is an in-ground pool that was built a little over a year ago with a plaster finish (technically its DiamondBrite).

Anything to be concerned about?

 

[Patrick_B]

Just a couple? Any chance you know of something being left in the pool that could have caused them?

 

[cheezedawg]

Just a couple. The biggest one is maybe 1/4 inch across, and I saw that one a few months ago. But yesterday I noticed a little grouping of some smaller ones in a different area.

This is on a caribbean shelf. Nothing that I know of has been left in the pool that could cause this.

 

[Patrick_B]

Well shoot, I was hoping you would say yes. Perhaps someone else will weigh in soon. No issues with water discoloration after high chlorine, or big ph swings?

 

[cheezedawg]

Aside from battling white flakes from my SWG, I don't have any big chemistry issues. Water is clear and always close to balanced (can't say it is completely balanced given the white flakes...)

 

[Patrick_B]

Any chance you can post a recent set of numbers? I would guess at a pH, CH, and or a T/A issue with the flakes. You shouldn't have that, so something is out of whack. If you could fill in the following below, it would help us help you.

FC
CC
pH
TA
CH
CYA

 

[JamesW]

It might be from inside the concrete, such as wire ties that were left too high and are bleeding through, or it might be something metal that got into the pool.

Some possibilities:

1) If a wire brush was used in or around the pool, bristles might have broken off and caused iron stains.
2) Using steel wool around the pool.
3) Cutting steel around the pool can leave metal bits.
4) Hair pins.

Try scratching them off with something hard and sharp. But, be careful not to gouge the plaster. A clean, smooth stainless steel knife usually works well. If the spots scrape off easily, then it's introduced contaminants. If the spots do not scrape off, then they are likely to be coming from inside the plaster.

If you don't like the idea of using a knife, try something abrasive, such as wet/dry sandpaper, a good stainless steel brush made for pool use, or a tool that is made specifically for removing rust stains from plaster.

http://www.ebay.com/itm/Pumice-Stone-EZ ... 1024971433


Note: Wire ties are the wires used to tie rebar together at the intersections.

If you're still not sure after trying the scrape test, a picture might help us determine what the cause is.

 

[Patrick_B]

Thanks James. I really didn't want to go out onto the limb, but sure was thinking rust from below. I know its just a possibility, but I didn't want to ring the alarm bell to quickly. Thanks for the tips on troubleshooting it.

 

[cheezedawg]

Any chance you can post a recent set of numbers? I would guess at a pH, CH, and or a T/A issue with the flakes. You shouldn't have that, so something is out of whack. If you could fill in the following below, it would help us help you.

Sure. I was planning on waiting to see if I could solve the problem before posting this in the chemistry forums above, but since you asked, I just went out and measured these tonight:

FC 6.0
CC 0.0
pH 7.3-7.4
TA 70
CH 475
CYA 60

I installed an intelliph earlier this year so my pH should stay pretty consistent. My pool temp is 80 today, so as far as I can tell I should be balanced. I've been dialing the pH down some to see if that helps- I had it closer to 7.5 before.

I recently raised my TA from 50 to 70 and that might have made things worse, but I had the flakes even before that change.

 

[cheezedawg]

It might be from inside the concrete, such as wire ties that were left too high and are bleeding through, or it might be something metal that got into the pool.

Some possibilities:

1) If a wire brush was used in or around the pool, bristles might have broken off and caused iron stains.
2) Using steel wool around the pool.
3) Cutting steel around the pool can leave metal bits.
4) Hair pins.

Try scratching them off with something hard and sharp. But, be careful not to gouge the plaster. A clean, smooth stainless steel knife usually works well. If the spots scrape off easily, then it's introduced contaminants. If the spots do not scrape off, then they are likely to be coming from inside the plaster.

Note: Wire ties are the wires used to tie rebar together at the intersections.

If you're still not sure after trying the scrape test, a picture might help us determine what the cause is.

Okay- I'll try scratching them off and report back. I havent used a wire brush or steel wool in the pool.

If it is coming from inside the plaster, are there any long term problems with the rust?

 

[JamesW]

If you don't like the idea of using a knife, try something abrasive, such as wet/dry sandpaper, a good stainless steel brush made for pool use, or a tool that is made specifically for removing rust stains from plaster.

Rust is mostly cosmetic. However, if water is getting down to steel wire ties or even rebar, then the metal will continue to rust. As it rusts, it will expand and cause some damage as it pushes through the plaster. Typically, this is not a huge deal, but it can be an annoyance as it is difficult to permanently repair.

Stain Erasers

http://www.lesliespool.com/Home/Pool-Ch ... 20186.html

http://www.thestaineraser.com/

Do the stains form a pattern that would suggest that they are from particles coming from returns?