Ascorbic Acid treatment

[Jimbob86]

Hi Everyone,

My name is Jim, I am a Brit living in south west France.
We bought the house 4 years ago and with it an inground pool, I believe
it could be fibreglass or vinyl but not entirely sure. I top up the pool with
water from the mains supply.

After opening up the pool after the winter season I find the sides and bottom are clouded
with a grey/brown stain. I have read lots of posts on here with advice on stains and as I had a ready supply of vitamin c tablets ( my wife takes them once a day) I decided to try the Vitamin c tablet test on the stain.
Bingo ! It returned the area around the stain to a vivid blue, the colour it should be all over and the stain around the area was gone. I am very impressed, and quickly ordered 1kg of Ascorbic Acid to carry out the treatment as described in an article on the forum. Now here's the bit I don't quite understand:

I lower the chlorine level to zero (or near) then introduce the Ascorbic Acid, This hopefully will remove all the staining but from what I have read on here the stain remains in the pool in a soluble state. I dont understand the next bit of introducing some sort of chemical to keep the stain in soluble state. This would mean more chemicals on a weekly/ monthly basis which I would prefer to avoid. I have also read about a gizmo which you put in the pump basket which will collect the stain these are very expensive and from my research it doesn't always seem to work. So after the AA treatment I understand I should bring the chlorine and ph levels back to normal, but......I should expect the stain to return?? The AA treatment sounds just what I need to get the pool back to looking nice for our summer season but would appreciate any help or advice from what appears to be a very knowledgable group of people. When we first moved to France it was a steep learning curve to keep the pool looking good and getting the chemical balance right and I thought I had done a good job, now this comes along and has given me anther mountain to climb I enclose a couple of pictures. I partially drained the pool to below the jets and skimmer for frost protection during the winter but I have not yet topped it up again until I have resolved the problem..I plan to top up before I apply the AA. Thanks again for any advice you can give. Look after yourselves and stay safe with this nasty virus going around. Best regards Jim.
Sorry the post is so long

 

[Texas Splash]

Welcome to TFP! So yes, you appear to have iron in the water which causes the stain. If you cannot change the water with fresh water that has no iron, the stains you remove from the walls simply go into a soluble state. The iron will try to go back out onto the pool surfaces when either the FC gets too high, the pH gets too high, and/or the iron content in the water increases. All 3 are major contributors. Ideally, you want to change-out the iron water, but that's not always possible. That's why a good sequestrant is used to help keep iron in a soluble state in the water. You can read more below. Hope that helps.

Stains in Your Pool

The stained pool is beyond embarrassing. Our in-depth Guide to remove stains in your pool will help you to remove the stains and prevent them in the future.

www.troublefreepool.com

Ascorbic Acid Treatment - Further Reading

www.troublefreepool.com

 

[Jimbob86]

Welcome to TFP! So yes, you appear to have iron in the water which causes the stain. If you cannot change the water with fresh water that has no iron, the stains you remove from the walls simply go into a soluble state. The iron will try to go back out onto the pool surfaces when either the FC gets too high, the pH gets too high, and/or the iron content in the water increases. All 3 are major contributors. Ideally, you want to change-out the iron water, but that's not always possible. That's why a good sequestrant is used to help keep iron in a soluble state in the water. You can read more below. Hope that helps.

Stains in Your Pool

The stained pool is beyond embarrassing. Our in-depth Guide to remove stains in your pool will help you to remove the stains and prevent them in the future.

www.troublefreepool.com

Ascorbic Acid Treatment - Further Reading

www.troublefreepool.com

Hi folks,
Hope you are all safe and well. I have a further problem that I need your advice with:
I am preparing the pool for AA treatment but the PH is at 7.9 so I put some PH- chemical in this morning and this afternoon I find this was the result.......see photo. So now I am not convinced that I have a metal problem as the PH- has cleaned part of the bottom of the pool. any thoghts on this would be appreciated.

Welcome to TFP! So yes, you appear to have iron in the water which causes the stain. If you cannot change the water with fresh water that has no iron, the stains you remove from the walls simply go into a soluble state. The iron will try to go back out onto the pool surfaces when either the FC gets too high, the pH gets too high, and/or the iron content in the water increases. All 3 are major contributors. Ideally, you want to change-out the iron water, but that's not always possible. That's why a good sequestrant is used to help keep iron in a soluble state in the water. You can read more below. Hope that helps.

Stains in Your Pool

The stained pool is beyond embarrassing. Our in-depth Guide to remove stains in your pool will help you to remove the stains and prevent them in the future.

www.troublefreepool.com

Ascorbic Acid Treatment - Further Reading

www.troublefreepool.com

Hi again everyone,
My tale of woe continues............I am prpearing the pool to carry out the AA treatment and the PH is still very high.
I added PH- yesterday and when I checked the pool this morning I found that where I had add the PH- the pool floor was clean !! Has anyone any thoughts on this?? Am I going in the wrong direction with the AA treatment? Should I be doing something different? The sides and the rest of the bottom of the pool is still dirty, it wont brush off but the reaction to the PH- has cleaned some of it. Where do I go from here< do I still carry out the AA procedure??
Thanks again for any assistance offered. Stay safe, cheers Jim

 

[Texas Splash]

I am not convinced that I have a metal problem as the PH- has cleaned part of the bottom of the pool. any thoughts on this would be appreciated.

Good question Jim. However in your first post you clearly confirmed there is some iron in the water by removing stains with the Vitamin C tablets. However, I do think it's time we back-up a bit and look at your whole situation one more time from the beginning. Is there any way you can provide a full set of test results? I'm curious to know ALL of your current readings (FC, CC, CYA, PH, TA, CH). The title of your thread is about AA, and we went straight to it based on the Vitamin C results, but your water also looks a bit like cloudy/algae. You may have both happening, so test results would be ideal at this point.

The pH control product you added, was it muriatic acid? Muriatic acid can effect a couple things like calcium scale, but can also help to control iron in the water if the pH is too high. I don'tr recall seeing it effect a surface like this however unless it settled quickly. Was the pump running when you added the pH lowering product?

So let's watch for your reply and hopefully some test results and we'll make sure we have a good decision from there.

 

[Jimbob86]

Good question Jim. However in your first post you clearly confirmed there is some iron in the water by removing stains with the Vitamin C tablets. However, I do think it's time we back-up a bit and look at your whole situation one more time from the beginning. Is there any way you can provide a full set of test results? I'm curious to know ALL of your current readings (FC, CC, CYA, PH, TA, CH). The title of your thread is about AA, and we went straight to it based on the Vitamin C results, but your water also looks a bit like cloudy/algae. You may have both happening, so test results would be ideal at this point.

The pH control product you added, was it muriatic acid? Muriatic acid can effect a couple things like calcium scale, but can also help to control iron in the water if the pH is too high. I don'tr recall seeing it effect a surface like this however unless it settled quickly. Was the pump running when you added the pH lowering product?

So let's watch for your reply and hopefully some test results and we'll make sure we have a good decision from there.

Hi Texas,
Thanks for your swift response, I am really keen to get this sorted out asap
I am still a novice when it comes to pool chemistry, I have a liquid testing kit where you put drops into a sample of pool water. This is telling me the chlorine is at aroun 3.0 and PH is about 8.2. I have an electronic PH meter which confirms this at 8.18. I also have test strips which shows FCI,ALK, and PH. I have dipped a test strip and included the photo,s below. I am so sorry, the rest of the initials you quote mean nothing to me :-( The PH- chemical is HYDROGENOSULFATE DE SODIUM (french) which translates to SODIUM HYDROGEN SULPHATE. Dont know if that helps ? We are in total lockdown here in France so I cannot take a sample of pool water for testing anywhere. Perhaps these results will be enough for you to take an educated guess at what is going on? Again many thanks for your expertise, without it I would really be struggling. Because of lockdown I am on my own as I cannot even call in a pool expert. Cheers Jim

 

[ajw22]

Post pics of the labels on the bottle of pH- you used.

 

[Jimbob86]

Post pics of the labels on the bottle of pH- you used.

Hi AJ,
Thanks for post, here is a picture of the tub. Translates to SODIUM HYDROGEN SULPHATE. Thanks Jim

 

[Texas Splash]

The SODIUM HYDROGEN SULPHATE you used is basically dry acid. Not ideal because of some potential side effects, but sometimes is all you have to use.

 

[ajw22]

So sodium bisulfate acid lifted unknown stains from your fiberglass pool the same way Ascorbic Acid did.

That is great. Either works for you. If the surface is now clean then no reason to do the AA treatment.

I think it is likely that whatever stained the pool is in solution in the water now and if you let the pH rise too much it will redeposit. Can you exchange the water and get fresh water in the pool?

 

[Texas Splash]

Jim, with limited water testing capabilities and local COVID restrictions, you may have some challenges. But you seem to show reactions to potentially two metals in your pool: Vitamin C (iron) and dry acid (copper). Some additional thoughts as you try to manage the pool with your limited supplies during the COVID lock-down:
- Copper is generally introduced to the water either by algecides or from copper plumbing (either from the supply line or internal heater core if installed).
- Iron generally comes from the local water supply; a well is very common; some local plumbing may also rust and contribute to iron
- Whether iron or copper, when the levels grow too much (usually over 0.3 ppm), the metal reacts much faster to chlorine and/or an elevated pH.
- There are two things you want to do right now; avoid algae by maintaining a reasonable FC (free chlorine) level. We do this by referencing the FC/CYA Levels. But you have to have an accurate CYA test to know what your FC should be, and that may prove difficult for you at the moment. Just do the best you can. The other is the pH. As Allen noted, you have to keep it well controlled. You might try to lower the pH to about 7.2-7.4 for now and let the water mix for the day. Monitor it to see if it helps at all. I would not let the pH exceed 7.6 for a while. The reaction you see (staining) all depends on those 3 factors: levels of the metal(s), FC, and pH level).

Not sure if you are able to get a good test kit mailed to you. In the states we use the TF-100 or Taylor K-2006C test kit. Either one is outstanding. To control metals after treatment and removing stains, we suggest using a good sequestrant. That product helps to keep the iron/copper in the water in soluble form so that it doesn’t go to the pool surfaces.

Don't forget to update your signature with all of your fiberglass pool and equipment info. It might help later. Give those things some thought and let us know how it turns out.

 

[Jimbob86]

Jim, with limited water testing capabilities and local COVID restrictions, you may have some challenges. But you seem to show reactions to potentially two metals in your pool: Vitamin C (iron) and dry acid (copper). Some additional thoughts as you try to manage the pool with your limited supplies during the COVID lock-down:
- Copper is generally introduced to the water either by algecides or from copper plumbing (either from the supply line or internal heater core if installed).
- Iron generally comes from the local water supply; a well is very common; some local plumbing may also rust and contribute to iron
- Whether iron or copper, when the levels grow too much (usually over 0.3 ppm), the metal reacts much faster to chlorine and/or an elevated pH.
- There are two things you want to do right now; avoid algae by maintaining a reasonable FC (free chlorine) level. We do this by referencing the FC/CYA Levels. But you have to have an accurate CYA test to know what your FC should be, and that may prove difficult for you at the moment. Just do the best you can. The other is the pH. As Allen noted, you have to keep it well controlled. You might try to lower the pH to about 7.2-7.4 for now and let the water mix for the day. Monitor it to see if it helps at all. I would not let the pH exceed 7.6 for a while. The reaction you see (staining) all depends on those 3 factors: levels of the metal(s), FC, and pH level).

Not sure if you are able to get a good test kit mailed to you. In the states we use the TF-100 or Taylor K-2006C test kit. Either one is outstanding. To control metals after treatment and removing stains, we suggest using a good sequestrant. That product helps to keep the iron/copper in the water in soluble form so that it doesn’t go to the pool surfaces.

Don't forget to update your signature with all of your fiberglass pool and equipment info. It might help later. Give those things some thought and let us know how it turns out.

Hi again Texas,

Thanks for all your advice, I will check out testing kits. Meanwhile should I add more PH- to try to reduce the PH ? Do you think by adding more PH- it will clean the rest of the pool? Would too much damage the pool. So sorry, more questions !! Take care and thanks Jim

 

[Texas Splash]

Definitely lower and control the pH. Whether it helps to eliminate existing staining is hard to know. But lowering the pH should help to prevent future staining. Make sure to have the pump running when dispensing the acid and give it some brushing if needed to keep it from settling in one spot on the floor.

 

[ajw22]

As Pat pointed out you may have a mix of iron and copper staining. So dry acid lifting some stains and AA lifting others. You have to see what works on the different areas of the pool.

But understand lifting the stains are temporary and they will eventually redeposit on pool surfaces unless you have a plan to drain the contaminated water and get clean water in the pool.