Stains re-appearing after acid wash

vinG96

New member
Feb 7, 2025
2
San Luis Obispo CA
Hello,

We had just had our plaster re-done in the spa. They had a tech coming out to adjust the chemicals in order to ensure everything was in tact before being completely finished with the job. Before the tech could even consider the job finished we started noticing brown stains appearing around the spa, initially a large stain on the seating area. The tech said it was odd, but we let it go for a while. Eventually the brown stains turned blue, and we had the head boss come out to see for himself. They told us they weren't sure how it happened, most likely copper from our heating furnace. They told us it would be a simple fix by using a water in acid wash bath to remove the stains. This worked nicely and made the plaster look good as new, but now, about a month later, I am starting to see the same exact stains reappear. Not just random stains, the same exact stain that we initially found on the seating area is back just as clear as before in a brown color. They are telling us its because the chemistry isn't correct, but I check the chemicals and make sure they are in tact every morning, and we even added a copper floculent to remove any potential metals. They came out after the acid wash and did a spin lab for us showing 0.2 copper. This is a 650 gallon spa. I just find it odd that the exact shaped stains are back, and they're blaming chemistry, when in fact this occurred when their own tech was performing the introductory chemistry. The larger image of the Spa was pre acid wash and the circled stain is post acid wash. The stain on the seating area is the same stain in the circled picture.

Could someone give me more information on this ? What could the issue be? Is this potentially due to poor plaster procedures ? 20250102_085243.jpg
 

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Welcome to TFP.

Show us pictures of the bottle and ingredients in the copper floculent you added.

A sequestrant does not remove metals from water. It just keeps metals in solution so they do not deposit on surfaces. And they do not lift metal stains that have deposited on surfaces.




What model heater do you have?

How old is it?

Shows us pictures of your equipment pad.

Do you have a test kit and know your water chemistry?

Metal staining is not caused by poor plaster procedures.
 
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I believe the Raypack furnace was installed around 10 years ago. After the initial service we suddenly had problems with the furnace. The plaster turned brown, then eventually blue, and shortly after pump went out on the furnace. The plaster/pool company installed IPS vidapure controllers, that have quite frankly caused more bad than good in my opinion. It seems like it just has a mind of its own halt the time. Our weekly pool servicer added the metal magnet and some pouch inside the motor skimmer. He said it'd eventually turn orange, but I haven't seen any color changes yet.

As far as my testing procedures, I test every morning, but not over the weekends. I use a taylor testing kit that covers chlorine, Ph, alk, hardness, and CYA. I primarily use Orenda app to calculate chemical adjustments, and the test kit pamphlet charts to double check if the sensors are accurate.
 

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