Acid Wash vs Jack's Copper Stuff to remove copper stains in in-ground spa; can a damaged heater leak copper into the pool without a low pH?

QPSUtah

Gold Supporter
In The Industry
Sep 12, 2024
110
Salt Lake City
Have a client that seems to have persistent low pH issues. They were using tri-chlor tabs which we suspect is the culprit (although, they used them for several months without any issue, then suddenly were having low pH problems). We previously did a drain and acid wash for them and it seemed to work well in removing the copper stains. Now the copper staining is back again. I'm a little concerned about doing a second acid wash, though maybe it wouldn't have any real effect. So my question is whether Jack's Magic Copper Stuff is more effective than an additional acid wash to remove the stains. They do not have a heater bypass, but given it is a small body of water, I could likely just put directly in, turn the heater off, let it lift the stains, and then drain.

The only complication is the pool is at elevation in the mountain west with temperatures likely to get into the teens the next couple of nights, so would worry about the equipment sitting idle and the water not being heated if done right now. I suppose we could "close the spa", and drain the pump/heater, blow out the lines while the "stuff" worked it's magic.

Secondly, can a damaged heater deposit copper into the pool even when the pH/LSI is good?

Thanks in advance!
 
.So my question is whether Jack's Magic Copper Stuff is more effective than an additional acid wash to remove the stains.

Jack's Magic Copper stuff is sulfmaic acid which is a milder acid to plaster than muriatic acid.

They do not have a heater bypass, but given it is a small body of water, I could likely just put directly in, turn the heater off, let it lift the stains, and then drain.

Do you mean turn the PUMP off?

The only complication is the pool is at elevation in the mountain west with temperatures likely to get into the teens the next couple of nights, so would worry about the equipment sitting idle and the water not being heated if done right now. I suppose we could "close the spa", and drain the pump/heater, blow out the lines while the "stuff" worked it's magic.

Staining is cosmetic.

Why not wait until warmer temperatures?

Secondly, can a damaged heater deposit copper into the pool even when the pH/LSI is good?

The copper heat exchanger develops a layer of calcium scale that protects the bare copper from erosion.

Low pH strips the protective calcium off the copper. Once the copper is exposed chlorine and water flow can erode the copper even at normal pH.

When the low pH is fixed you need to let the heater rebuild the protective calcium to stop copper erosion.
 
Is it this one?


What are the readings now?

Are you still using trichlor?
 
  • Like
Reactions: QPSUtah
Jack's Magic Copper stuff is sulfmaic acid which is a milder acid to plaster than muriatic acid.



Do you mean turn the PUMP off?



Staining is cosmetic.

Why not wait until warmer temperatures?



The copper heat exchanger develops a layer of calcium scale that protects the bare copper from erosion.

Low pH strips the protective calcium off the copper. Once the copper is exposed chlorine and water flow can erode the copper even at normal pH.

When the low pH is fixed you need to let the heater rebuild the protective calcium to stop copper erosion.
Thanks for the reply. I'll probably instruct the client to wait until the spring to address the staining. And yes, I meant turn the pump off, not the heater off. Although at this point, I'll likely replace the heat exhanger in the heater for them anyway. So maybe it wouldn't be a big deal to just run the copper stuff through the heater and replace the heat exchanger when done (unless there are other components of the heater that could be damaged...)
 
Is it this one?


What are the readings now?

Are you still using trichlor?
We told them to stop using trichlor back in October, but have still found the floater in the pool on occasion, and the pH is back to being low. So not sure if it's the trichlor or something else. Moving forward, I've been very clear to them to just manually dose liquid chlorine before and after using the pool. We'll see if that keeps the pH more stable.

The strange thing is, looking at their past readings, even though they were using the tablets, the Ph was in the mid 7's for months up until August of this year. Maybe the CYA built up, impacted their alkalinity, and couldn't buffer the pH well enough any more and we didn't do enough to counteract the alkalinity.
 
How low?

What are all readings?
We read 6.0 pH and TA of 40 on 11/4 and 6.4 pH and TA of 40 again on 11/18. I'm just guessing it's the Trichlor that is lowering it. But I spent time with them yesterday instructing them on using liquid chlorine moving forward, so hopefully we've permanently removed that variable from their system. I'm also attaching a new picture of the recent, I assume copper deposits, on the plaster again. Very deep blue. It seems to actually come off the grout onto their skin when they sit up against it.
 

Attachments

  • IMG_1576.JPG
    IMG_1576.JPG
    446.1 KB · Views: 14

Enjoying this content?

Support TFP with a donation.

Give Support
Probably copper.

Maybe some copper cyanurate as well as other copper compounds.

Can you pull the filter cartridge to see if it has copper residue?

What is the CYA level?

How are you reading the pH at 6.0?
 
Last edited:
Probably copper.

Maybe some copper cyanurate as well as other copper compounds.

Can you pull the filter cartridge to see if it has copper residue?

What is the CYA level?

How are you reading the pH at 6.0?
That's a really good question re pH reading, LOL. Hadn't stopped to think of that... I'll have to follow up with the tech why they wrote that down. The things we don't always think off... We'll look at the filter cartridge next time we're up there.
 
  • Like
Reactions: JamesW
TFP is a registered 501(c)3 non-profit that is maintained by user donations.

All of our content is free of advertisements.

Please consider donating at:

 
TFP is a registered 501(c)3 non-profit that is maintained by user donations.

All of our content is free of advertisements.

Please consider donating at:

I'm now a proud gold member!!
 
We're all volunteer here so every donation basically extends the date that the site goes dark. It ensures that we'll be around longer to help folks out and none of us wants to have to find a new hobby. THANKS for helping us help you. :)
 
  • Like
Reactions: JamesW
Following up on this post. I’m curious how big of a difference temperature makes in an acid wash.

We replaced the heater for them and balanced the water. Something seems to have oxidized the copper staining after draining and filling. Customer is complaining the copper staining is turning black.

So considering doing an acid wash for them. We expect temperatures in the low to mid 40’s this week so would definitely be above freezing. Any drawback of doing an acid wash in those temps? Would it still be pretty effective? I assume the chemical reaction slows and becomes less effective at some point, but can’t find explicit temperature recommendations anywhere.
 
Temperature should not affect the effectiveness of an acid wash, however, I would avoid an acid wash because it is just too damaging to the plaster.

I would probably try sulfamic acid first and then go to zero alkalinity if the sulfamic acid did not work 100%.

Take the equipment offline and even drain the equipment during the treatment.

Brush the pool to help circulate the sulfamic and remove the stains.

Then, drain and refill if it is safe to do so.

 
Last edited:
Note that a light can be damaged by acid, so maybe pull the light up on the deck during treatment.

Metal light niches, handrails and other metal objects can also be damaged during treatment.
 
Temperature should not affect the effectiveness of an acid wash, however, I would avoid an acid wash because it is just too damaging to the plaster.

I would probably try sulfamic acid first and then go to zero alkalinity if the sulfamic acid did not work 100%.

Take the equipment offline and even drain the equipment during the treatment.

Brush the pool to help circulate the sulfamic and remove the stains.

Then, drain and refill if it is safe to do so.

Remind me how long the sulfamic acid needs to remain in circulation. Due to the cold temperatures, yes, we'd have to drain the equipment if it isn't circulating at all.
 

Enjoying this content?

Support TFP with a donation.

Give Support
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.