Stain in plaster after repairs

[lborne]

Finally, after over 6 months, the 3 spots in my pool where rebar was rusting through were correctly fixed. The pool was drained half way to get to the lowest spot. The other 2 spots were behind the water line tile.

Anyway, the grinding and cutting disks made quite a mess cutting back rebar. When I came home, there was a mess on the bottom of the pool. Large brown areas along the bottom wall edge starting from where the repairs were done and extending several feet. I vacuumed, but it did not all come out. Its stained the plaster brown. I dropped the pH and brushed and its 90% gone. But no matter how much I brush, I can't get the final little bit out. If I pour muratic acid right on a spot using a pipe, it clears that spot, but I don't want to add any more acid at this point. And I'd rather not pour in some stain remover from the pool store until I know what it will do to the pool. Any ideas?

 

[frustratedpoolmom]

What is the "stain remover"?
How much more stain is left? If you add the acid as you did to remove the stains, you can always add soda ash/borax/baking soda to adjust PH and TA later that same day. Lowering it temporarily won't be much harm, as long as you adjust it back. Just be sure to use some sort of sequesterant to prevent what is causing this stain from redepositing on the surface.

 

[lborne]

I have not added any "stain remover". Just thought that if I go into a pool store, they will try to sell me something like that. I'd adjust the pH back up and then spot apply acid to remove the stains. Its pretty much gone - but you can still see a darker area compared to the rest of the pool.

Of course, I could just call the guy that did the repair back, but in my experience, the more people work on my pool, the worse it gets.

 

[lborne]

I called the pool guy that did the repairs and asked what I should do. At first he said it was from my well fill water. When I said it was city water, he then agreed that the stains could be from the rebar dust after it settled to the bottom. He suggested pouring in 4 gallons of acid and brushing as often as possible for 3 or 4 days, and then bringing the pH back up with soda ash. He said I should bypass my heater and that the acid would not hurt the other parts of my system - filter, pump, valves, solar panels, etc.

Does this sound good? I think I can add the acid via a pipe to be more concentrated on the stains at least for a few moments, and that has proven to work. But then what do I do to get my TA back in line? And where can I buy soda ash to get the pH back up?

 

[Johnny Tikinut]

Hi Everyone,

I don't know whether or not my problem is the same, but it seemed similar. I drained my pool back around Thanksgiving (2010) due to extremely high CYA (250-300). I had the problem of the pool turning green just as described in TFP Pool School.

Now upon refilling from "city water" and meticulously balancing my pool as per TFP standards I am finding small BB size spots appearing. It seem as though I get a couple new ones each week on average. Are these spots possibly copper rust from my equipment? Could they be something that has come in with rain? We had an extraordinary amount of rainfall by southern California standards this last December (about 10 inches). I took over as my own pool man a few weeks before the pool went green and most of the balances were way out of whack. I'm not sure that I was getting correct readings due to CYA, and I was also very green (much like my pool at the time), so please don't ask me what my levels were prior to drainage. I have been very consistent with keeping the chlorine levels correct since the refill, and began using bleach January 1st after 10 years of Trichlor.

Thank you in advance for any help that you can offer.

STATS:

Chlorine - 4 PPM (Using Bleach)
pH - 7.8
Alkalinity- 85 PPM
CH - 280 PPM
CYA - 35-40 PPM

 

[Johnny Tikinut]

I just noticed that the stains that 5 or 6 weeks ago looked "BB" sized (probably magnified by the water), now look Pea sized. I also have almost a cluster of sorts of tiny ones smaller than I've seen before, although it's possible that my awareness may have been heightened by the appearance of the prior spots. The BB and pea sized spots look very round, and most of the new tiny spots are more rice shaped.

 

[frustratedpoolmom]

You need to determine if the stains are metal in nature or organic. Hold a trichlor tablet on the stain, if it fades, the stain is organic. Hold/rub a vitamin C tablet on the stain, if it fades the stain is metal. Post back, and we'll probably begin your own thread.

 

[Johnny Tikinut]

Hi Mod Squad Mom,

Thank you for your response. It ended up being the Vitamin C that faded it. So what can I do to get rid of, or contain my metal? I saw earlier that you mentioned managing metals by using a sequestrant. Of course I'm also curious what you would recommend to remove the existing rust spots.

 

[zea3]

Hi Mod Squad Mom,

Thank you for your response. It ended up being the Vitamin C that faded it. So what can I do to get rid of, or contain my metal? I saw earlier that you mentioned managing metals by using a sequestrant. Of course I'm also curious what you would recommend to remove the existing rust spots.

If the metals in the water came from your source, then you will need a sequestering agent such as the Jack's (color) Stuff. Which Jack's product you would need would depend on what kind of metal you have in the water. You need to test your source water to find out if it contains metal and which one. Your local pool store should be able to test this for you.

If your source water does not have metals, then they came either from a product previously used in the pool or a degrading copper component in the plumbing system.

Either way, you can remove the stains with an absorbic acid treatment. You can decide whether or not to drain and refill if the source of metal is not from your fill water.