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Light Brownish Stains At Near Bottom And Some Sides Of Pool


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When I use Ascorbic Acid [Vitamin C] it works well to remove the stains. ..(just opened pool a few weeks ago). Problem is why did the stains happen and during the summer months how do I prevent the pool from getting this type of brownish stains? As it is expensive to keep putting about 5-6 lbs of Ascorbic Acid to remove the stains every other month? If metals are coming in how? Is it the metal ladder we have in the inground pool? Advise? I put in culator... and I believe it works but that is also very expensive. Water chemistry is all totally balanced [ph, alkalinity, etc etc] by the pool company that opened it. I think they is maybe metal in the water and we use Natural Chemistry -Metal Free to remove dissolved metals in it along with Culator Metal Remover. What else can be done. When I use Ascorbic Acid it works nearly within 1hr to remove the stains on a 24,000 gallon pool.

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The stains happen because there are metals in your water, most likely iron. It could be present in the water in your local or it could have come from metal in your pool "rusting".

Ascrobic acid will convert the insoluble metal stain to a different oxidation state that is colorless and soluble so the stain 'disappears' and the metal goes back into solution in pool water. However, the metal is still there ready to restain!

Seqestrant will help prevent that. It chemically 'deavtivates' the metal ions in the water so they cannot redeposit as stain but sequestrants do break down over time so they need to be reapplied on a regular basis to keep the metals in the colorless form and in solution.

There are two sequestrants that a generally used in pools and spa:

EDTA

HEDP and other phosphonates.

EDTA is found in all the "phosphate free" metal sequestrants. IMHO, it does not work well

HEDP and related chemicals are found in the ones that work such as the ones from Jack's Magic, Proteam, Haviland, and many other companies

Metal Free is EDTA which is not that effective at sequestering metals. Try a phosphonic acid based sequestrant like Jack's Magic or Proteam Metal Magic. IF the stains are reappeing you need to:

1) watch that your pH does not climb above 7.8 (VERY IMPORTANT!!!)

2) add your maintenance dose of sequestrant weekly.

Remember, that these "metal removers" do NOT remove the metals from the water, they just chemically "deactvate" them so they cannot deposit as stain BUT they are broken down by chlorine and sunlight so they do need to be reapplied on a regular basis.

If you see stains starting to reappear during the summer then IMMEDIATELY add a full dose of sequestrant and drop the pH to 7.0 and keep it there until the stains disappear, This will only work if you do it at the first sign of restaining. The pH will come up on its own eventually but don't let it go below 7.0 if you have a vinyl pool or you want to swim and check the TA to make sure it has not dropped too low. Be careful raising the TA or the pH.

If you need to add baking soda to raise TA DO IT IN VERY SMALL DOSES!!!!

IF you need to raise the pH because it dropped below 7.0 use borax and not pH increaser (soda ash) and pour it directly into the skimmer!

The ascorbic acid treatment will probably have to be done yearly.

Brown stains are normally iron (think rust) but sometimes copper can also produce a brownish stain. Iron stains are easily removed by ascorbic acid, copper stains are not.

IF you want to try and reduce the cost of adding sequestrant there are a few things you can try.

1) House brands are just as effective as the more expensive name brands so check out the house brands from your pool store or places like Ace Hardware. Just read the label. It should contain a phosphonic acid derivative, a phosphonate, HEDP, Etidronic acid. or 1-hydroxyethane 1,1-diphosphonic acid which are different names for basically the same active ingredient.

2) you can try a less frequent dosing interval. If weekly additions are keeping the stains away try dosing every two weeks. If you are staying stain free then only dose every two weeks instead of weekly. If stains come back then add a full dose of sequestrant and drop the pH as above.

Once you are SURE that dosing every two weeks will work for you you can try cutting back to monthly dosing. If your metal problem is not a bad one it could work. Once again, if the stains come back add sequestrant and drop the pH.

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The stains happen because there are metals in your water, most likely iron. It could be present in the water in your local or it could have come from metal in your pool "rusting".

Ascrobic acid will convert the insoluble metal stain to a different oxidation state that is colorless and soluble so the stain 'disappears' and the metal goes back into solution in pool water. However, the metal is still there ready to restain!

Seqestrant will help prevent that. It chemically 'deavtivates' the metal ions in the water so they cannot redeposit as stain but sequestrants do break down over time so they need to be reapplied on a regular basis to keep the metals in the colorless form and in solution.

There are two sequestrants that a generally used in pools and spa:

EDTA

HEDP and other phosphonates.

EDTA is found in all the "phosphate free" metal sequestrants. IMHO, it does not work well

HEDP and related chemicals are found in the ones that work such as the ones from Jack's Magic, Proteam, Haviland, and many other companies

Metal Free is EDTA which is not that effective at sequestering metals. Try a phosphonic acid based sequestrant like Jack's Magic or Proteam Metal Magic. IF the stains are reappeing you need to:

1) watch that your pH does not climb above 7.8 (VERY IMPORTANT!!!)

2) add your maintenance dose of sequestrant weekly.

Remember, that these "metal removers" do NOT remove the metals from the water, they just chemically "deactvate" them so they cannot deposit as stain BUT they are broken down by chlorine and sunlight so they do need to be reapplied on a regular basis.

If you see stains starting to reappear during the summer then IMMEDIATELY add a full dose of sequestrant and drop the pH to 7.0 and keep it there until the stains disappear, This will only work if you do it at the first sign of restaining. The pH will come up on its own eventually but don't let it go below 7.0 if you have a vinyl pool or you want to swim and check the TA to make sure it has not dropped too low. Be careful raising the TA or the pH.

If you need to add baking soda to raise TA DO IT IN VERY SMALL DOSES!!!!

IF you need to raise the pH because it dropped below 7.0 use borax and not pH increaser (soda ash) and pour it directly into the skimmer!

The ascorbic acid treatment will probably have to be done yearly.

Brown stains are normally iron (think rust) but sometimes copper can also produce a brownish stain. Iron stains are easily removed by ascorbic acid, copper stains are not.

IF you want to try and reduce the cost of adding sequestrant there are a few things you can try.

1) House brands are just as effective as the more expensive name brands so check out the house brands from your pool store or places like Ace Hardware. Just read the label. It should contain a phosphonic acid derivative, a phosphonate, HEDP, Etidronic acid. or 1-hydroxyethane 1,1-diphosphonic acid which are different names for basically the same active ingredient.

2) you can try a less frequent dosing interval. If weekly additions are keeping the stains away try dosing every two weeks. If you are staying stain free then only dose every two weeks instead of weekly. If stains come back then add a full dose of sequestrant and drop the pH as above.

Once you are SURE that dosing every two weeks will work for you you can try cutting back to monthly dosing. If your metal problem is not a bad one it could work. Once again, if the stains come back add sequestrant and drop the pH.

Thanks so much for the reply. I truly appreciate it... many will as well. BTW I am thinking of converting to a Salt System Chlorination... will metal still be a problem? As I hate spending $100s on Ascorbic Acid and Metal Free Chemicals. The pool guy said with a SWGS this will be less of a problem. True? He said I do not need any of my 3 1/2 inch Chlorine tabs anymore. Should I just sell them? As I have a lot of other chemicals as well and not sure what needs to be kept and what I do not need any longer??

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Find the source of the iron. Are you filling with well water? There are metal filters available that fit on a hose.

Salt cells typically need baking soda and acid, either a product called Dry Acid or Muriatic. Unlike tabs that drive pH down, salt cells tend to do the opposite, raise it, hence the need for acid.

As waterbear said, EDTA is lame. It breaks down with exposure to chlorine fairly quickly.

HEDP is a more durable solution.

Scott

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I use City .... I believe.. what is HEDP? Is that available online? By the way with the Culator I use and the Ascoric Acid.. all the stains came off in less than a week.

HEDP = 1-Hydroxy Ethylidene-1,1-Diphosphonic Acid, it is a phosphonic acid derivative that is used in metal seqeustrants like Jack's Magic or Proteam Metal Magic and is more effective than EDTA, which is used in Natural Chemistry's Metal Free and othe "phosphate free" metal sequestrants.

Read the bottle. If it contains HEDP, phosphonic acid derivatives, phosphonates, or it's phosphonic acid based it's the good stuff. If it containd EDTA then don't buy it!

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Thanks so much for the reply. I truly appreciate it... many will as well. BTW I am thinking of converting to a Salt System Chlorination... will metal still be a problem? As I hate spending $100s on Ascorbic Acid and Metal Free Chemicals. The pool guy said with a SWGS this will be less of a problem. True? He said I do not need any of my 3 1/2 inch Chlorine tabs anymore. Should I just sell them? As I have a lot of other chemicals as well and not sure what needs to be kept and what I do not need any longer??

I wouldn't count on converting to a SWG system to solve your metal issues. I have a salt water pool and am in the same metal hell that you are in.

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Salt cells typically need baking soda and acid, either a product called Dry Acid or Muriatic. Unlike tabs that drive pH down, salt cells tend to do the opposite, raise it, hence the need for acid.

I believe you mean salt and acid. Baking soda is rarely needed in a salt pool. TA is normally best run around 70-80 ppm and most pools start off with a higher TA than that!

Saslt pools don't use soda ash and rarely need baking soda but the do require acid and less frequently salt and CYA (and borates if used)

Pool run on trichlor need mostly soda ash (or borax) and baking soda fairly regularly and very rarely need acid (unless the TA is TOO high) or CYA.

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  • 2 weeks later...

There are iron tests available. Some pool stores have may test for it, some don't. The iron test may be a billable test as they are somewhat expensive.

Never heard of a coffee cup stain. All stains are different sizes and shapes.

Scott

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I've been fighting light-brownish metal stains for months. I've repeatedly done the ascorbic acid treatment and after trying numerous products (Metal Free, Jacks Magic, Culator, various sequestants) I have finally found that Proteam's Metal Magic mentioned above seems to give me the best results. It didn't work as fast as ascorbic acid, but it still only took a few days to noticably clear the metal stains. They are not completely gone, but they are gone enough to where if nothing else happens I would be happy. I just added my first maintenance dose yesterday and hope it will continue to improve. The best past is, with Metal Magic you don't need to mess with your chlorine level or sequestrants. Leave your chlorine where it is (2-3ppm) and add Metal Magic and you're done. (Ph should be around 7.6 with this stuff)

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I've been fighting light-brownish metal stains for months. I've repeatedly done the ascorbic acid treatment and after trying numerous products (Metal Free, Jacks Magic, Culator, various sequestants) I have finally found that Proteam's Metal Magic mentioned above seems to give me the best results. It didn't work as fast as ascorbic acid, but it still only took a few days to noticably clear the metal stains. They are not completely gone, but they are gone enough to where if nothing else happens I would be happy. I just added my first maintenance dose yesterday and hope it will continue to improve. The best past is, with Metal Magic you don't need to mess with your chlorine level or sequestrants. Leave your chlorine where it is (2-3ppm) and add Metal Magic and you're done. (Ph should be around 7.6 with this stuff)

Metal magic is a HEDP sequestrant. I do like it but it is not really any different than any of the others like Jack's magic or even the (inexpensive by comparison) Ace Hardware housee brand O-Ace-Sis (which is also HEDP). It works as well as any other sequestrant at removing the stains, which is it reduces them somewhat but normally does not remove them completely. For that you need a reducing agent (antioxidant) such as ascorbic, citric, or oxalic acid.

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