Plan to get rid of metal stains

[steve53]

I did not test for CYA, assuming it is low to medium. I did have to add water this year, and the only CYA that gets in there is from the pucks that I usually use.

After first shocking the pool to make it swimmable, I decided to go after the stains after joining the forum.

I let the chlorine gradually fade away to zero, with the TA and pH in the good range.

I bought 10 pounds of bulk food-grade citric acid and put six pounds around the 30,000 gallon pool. Most of the stains disappeared, but not all. This is the first time I have gone after the stains in 4 years. So I added the rest- 10 pounds of citric acid in total.

My plan is to wait 24 hours, then put in 32 ounces of hth metal remover and let that perk for a few hours.

Now comes the question:

The pool was getting a little cloudy due to the lack of chlorine when I started. After the sequestering agent has had a few hours to do the job, would it be time to shock it with chlorine again? The pH should be ridiculously low and this shoulw maximize the chlorine doing its job.

Then, I have bulk baking soda ready to go to put in as much as I need to get the pH to 7.4 or so.

Good plan?

Thanks in advance.

 

[Azgirl71]

Never let your FC drop to 0. That is an open invite for algae to come play in your pool.

Can you post a full set of numbers and the kit you are testing with please?

This will help you a bit on metals
Pool School - Metals in the Water and Metal Stains

 

[jblizzle]

The FC has to drop for the AA treatment, but that is why the use of Poly 60 algaecide is recommended (in the very special case).

Also, verify that that sequestrant is on of the ones recommended in the link Lisa posted or has the same ingredients.

 

[steve53]

I bought this at WalMart- the hth metal remover. Is this not acceptable?

Will the sequestrant bond with the free iron and wind up in the filter? That's how I see it.

Then with a low-iron water pool I use the chlorine and balance to a normal TA and pH and a clear pool and that's it, right?

 

[Azgirl71]

It is not one of the recommended products to use, but that is up to you. If you can post the ingredients maybe someone with more experience in metals can help you determine if you should use it.

 

[jblizzle]

Usually a sequestrant just keeps the metal in suspension preventing stains (and you have to keep adding it). It does not usually allow the iron to be filtered out.

 

[steve53]

The active ingredient is hydroxyethylidene diphosphonic acid.

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I have a cartridge filter. Shouldn't some of the iron salts be filtered out when I get them off the vinyl of the pool? I am assuming that the positive iron ion would complex with the negative chloride ion when I shock it again.