Ascorbic acid treatment caused mottling - now what?

[mcgeechelle]

Hi all. Last summer I did an ascorbic acid treatment to my pool, which did wonders for cleaning off the steps and lightened my pool surface quite a bit, which I was pleased with, but it also caused a cheetah print/mottling on the surface. I assumed that I just needed to do another treatment, but didn’t have the supplies or time with company coming, so moved on with life thinking I’d try it again sometime in the future. I decided to do it again today since I noticed an ever so slight tanish color coming back to my steps (I slacked off on the sequestrant this winter, so not totally surprising; my fill water is hard, so I just have to keep it in suspension). Again, steps look amazing, but it doesn’t seem to affect the tan mottling on the walls or bottom to any real degree. I have scrubbed. Does this indicate some issue with my plaster? It not a new pool, built in 2004. I acquired it in 2014, so I don’t imagine it’s had any resurfacing done.

 

[ajw22]

I don't think the AA treatment caused those stains. The stains were probably under the metal stains and were exposed after the AA treatment. Go through the stain identification process described in ...

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

Place a trichlor puck on the stain for a few minutes to see if it lightens or removes the stain.

 

[mcgeechelle]

I don't think the AA treatment caused those stains. The stains were probably under the metal stains and were exposed after the AA treatment. Go through the stain identification process described in ...

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

Place a trichlor puck on the stain for a few minutes to see if it lightens or removes the stain.

Thanks, I will have to go through the guide since hours later I see no impact on the stains from the ascorbic acid. I have tried to scrub it with a trichlor pick before, but to no avail, which is why this is so confounding. I thought for sure it was metal.

 

[JoyfulNoise]

SO the pool has an unknown 10 year history of some kind of pool care....who knows what the last person was doing.

That looks like damaged plaster. Plaster mottling would show up shortly after the installation and it would be all over the pool. Those look more like the plaster has been etched by something. Perhaps the previous owner poured acid in that area to adjust pH and did not brush well OR they added powdered shock there (dichlor) which is mildly acidic and can cause etching.

Ascorbic acid will not help and I would not suggest you have anyone do any kind of acid washing as that will just damage the plaster further. At 16 years that plaster is considered "old" and probably just needs to be redone (chipped out and new plaster installed). Replastering can cost anywhere from $6k to $12k and upwards depending on the product and how much labor is done to chip out the old plaster. Start saving up for a remodel and just "learn to love" your pool's uniqueness.

 

[mcgeechelle]

SO the pool has an unknown 10 year history of some kind of pool care....who knows what the last person was doing.

That looks like damaged plaster. Plaster mottling would show up shortly after the installation and it would be all over the pool. Those look more like the plaster has been etched by something. Perhaps the previous owner poured acid in that area to adjust pH and did not brush well OR they added powdered shock there (dichlor) which is mildly acidic and can cause etching.

Ascorbic acid will not help and I would not suggest you have anyone do any kind of acid washing as that will just damage the plaster further. At 16 years that plaster is considered "old" and probably just needs to be redone (chipped out and new plaster installed). Replastering can cost anywhere from $6k to $12k and upwards depending on the product and how much labor is done to chip out the old plaster. Start saving up for a remodel and just "learn to love" your pool's uniqueness.

That mottling is widespread throughout the pool My pic was just my attempt to get a close up of one area in case the color was any indication to anyone. I don’t disagree that the previous owners did not take care of the pool well - I had to replace almost all of the equipment within the first year or so of living here, they were using some weird in-line copper bead sanitizer and I think they solely used trichlor for chlorine, as they left me a giant bucket of pucks, so the water very well could have been aggressive and maybe even more metal heavy with the deteriorating copper beads. I wondered if a resurfacing job wasn’t in my near-ish future, but I can live with it for now, cheetah spots and all. Thanks for the confirmation.

 

[JoyfulNoise]

If they used copper then you can try to see if the stains react to Jacks Magic Stain ID kit. The kit contains a process for checking if a stain is copper or mixed-scale (calcium scale plus impurities). Copper does not get lifted by ascorbic acid and is usually made darker when AA is applied.

If there is copper scale, then there’s a process to remove it. But, to be permanently rid of copper, you have to lift the stains and then drain the pool. Copper only leaves when it’s redissolved into the water and the water is replaced.

 

[mcgeechelle]

If they used copper then you can try to see if the stains react to Jacks Magic Stain ID kit. The kit contains a process for checking if a stain is copper or mixed-scale (calcium scale plus impurities). Copper does not get lifted by ascorbic acid and is usually made darker when AA is applied.

If there is copper scale, then there’s a process to remove it. But, to be permanently rid of copper, you have to lift the stains and then drain the pool. Copper only leaves when it’s redissolved into the water and the water is replaced.

Interesting! I did think some of my staining became a little more pronounced in some areas the first time I did the AA treatment but thought it was because my white plaster was brighter (although it could reasonably be a combination of both). I will order the ID kit just because I’d like to know. I can’t really afford to fully empty and refill the pool right now (and I’m in Fl with a high water table, so will have to do some research on how/when). It may be something I have to live with until I have the pool resurfaced. Thanks again.