Copper Issue from heater.

[FlDave]

I'll try to keep it short.

I have some large areas of staining that I suspected were from copper.
My suspicions are driven by the kids hair constantly turning green, as well as a spot test of a vitamin-c tablet having black color reaction with the stains before eventually disappearing.

I know what the cause is, and it's since been corrected. I was using an incorrectly calibrated PH meter for about 3-4 months last year. It dawned on me after seeing a blue/green substance in my filter.
I did the PH drop test with my TF100 and realized I was running the PH in the 5.7-6.8 range the entire time. (Ok lesson learned, and I'll only use the drop test from now on).

Here's my question. Obviously the copper was introduced from the heater coil as I have no other sources of copper including the city water.
I took the manifold off to inspect the corrosion damage.
Honestly, I think it looks "ok", the copper is nice an thick still but there is some red discoloration on the insides of the tubes.

I've reached out to Jacks Magic for support on the stain removal, but they are concerned about the Red Tint in the copper.
Should I run this coil out of it's remaining life or replace it? The heater is about 2 years old.

Also I understand a drain & refill is the only way to remove the copper so that will be on my list as soon as I get rid of the staining.

I'd love to hear your thoughts on the condition of the coil.

 

[JoyfulNoise]

The red color isn’t anything to worry about. That’s just what you get when you acid etch copper. The red color comes from one of the oxide that forms. Those tube look like they have been thinned out a bit. They are likely still functional but you’ll need to keep a close eye on your heater for manifold leaks. Replacing the heat exchanger is no small task and there’s any number of ways it can get screwed up. So if it were me I would simply run the heater for whatever life is left in it and then replace it when it dies. You never know, you may get many more years out of it.

I would be very careful with the Jacks Magic copper removal regimen. Their process uses sulfamic acid which causes false high CC readings for many many weeks as the sultanate slowly breaks down. I suggest you only run the stain removal process when you are ready to drain and refill.

 

[JamesW]

There are two stable copper oxides.

Copper(I) oxide or cuprous oxide is the inorganic compound with the formula Cu₂O, which looks like the reddish color that you see.

Copper(II) oxide or cupric oxide is the inorganic compound with the formula CuO, which is black.

Low pH strips off the protective copper oxide layers and allows oxygen and chlorine to attack and oxidize the copper metal.

 

[JamesW]

4Cu + O₂ --> 2Cu₂O (Reddish color).

2Cu₂O + O₂ --> 4CuO (Black).

2CuO + CO₂ + H₂O --> Cu₂CO₂(OH)₂ (Turquoise patina).

The hydrogen in acid does not directly oxidize the copper like it will do to aluminum.

However, the low pH continuously strips off any protective oxide layers, which exposes the copper metal directly to oxidation.

 

[FlDave]

4Cu + O₂ --> 2Cu₂O (Reddish color).

2Cu₂O + O₂ --> 4CuO (Black).

2CuO + CO₂ + H₂O --> Cu₂CO₂(OH)₂ (Turquoise patina).

The hydrogen in acid does not directly oxidize the copper like it will do to aluminum.

James very informative. What would be your stance if this was your heater? Replace it or Keep it running? Anything I can do to slow the process down since the chemistry is back in balance (IE. Adding a Zinc plate?)

@JoyfulNoise Any other copper stain removal processes you recommend instead? My wife and I have absolutely no problem swallowing the cost of the water replacement after treatment. My biggest concern is the pool popping if I have to drain more than 1/2. I've got a lake within 60-70ft and a pretty high water table. They actually had issues digging down 9 feet to install this pool without it getting washed out from ground water.

 

[JamesW]

It’s hard to tell how much damage has been done.

Once the metal gets chemically damaged, it is susceptible to more chemical damage and to mechanical erosion as the water has more friction with the now rough copper surface causing mechanical stripping and turbulence.

Sulfamic acid will also attack copper, so you don’t want to circulate sulfamic through the heater.

You can keep or replace the heat exchanger, but it might leach more copper and it might eventually leak.

A leak would probably ruin the heater and require a full replacement.

 

[JamesW]

New copper is a reddish color and it can turn brownish over time as it develops a copper oxide patina.

Reddish pink indicates that you have fresh oxidation where low pH has stripped off the patina and you have a mixture of raw solid copper and copper(I) oxide.

If the color goes to a darker brownish color, that can indicate the formation of a protective copper(II) oxide layer.

 

[JoyfulNoise]

@JoyfulNoise Any other copper stain removal processes you recommend instead? My wife and I have absolutely no problem swallowing the cost of the water replacement after treatment. My biggest concern is the pool popping if I have to drain more than 1/2. I've got a lake within 60-70ft and a pretty high water table. They actually had issues digging down 9 feet to install this pool without it getting washed out from ground water.

Bypass the filter and get a winterizing tube for the SWG (IC40). Do the sulfamic acid stain removal process and then do an exchange-drain of the pool -

Draining - Further Reading

www.troublefreepool.com

A no-drain exchange will remove the contaminated water and avoid floating the pool.

 

[1poolman1]

I'll try to keep it short.

I have some large areas of staining that I suspected were from copper.
My suspicions are driven by the kids hair constantly turning green, as well as a spot test of a vitamin-c tablet having black color reaction with the stains before eventually disappearing.

I know what the cause is, and it's since been corrected. I was using an incorrectly calibrated PH meter for about 3-4 months last year. It dawned on me after seeing a blue/green substance in my filter.
I did the PH drop test with my TF100 and realized I was running the PH in the 5.7-6.8 range the entire time. (Ok lesson learned, and I'll only use the drop test from now on).

Here's my question. Obviously the copper was introduced from the heater coil as I have no other sources of copper including the city water.
I took the manifold off to inspect the corrosion damage.
Honestly, I think it looks "ok", the copper is nice an thick still but there is some red discoloration on the insides of the tubes.

I've reached out to Jacks Magic for support on the stain removal, but they are concerned about the Red Tint in the copper.
Should I run this coil out of it's remaining life or replace it? The heater is about 2 years old.

Also I understand a drain & refill is the only way to remove the copper so that will be on my list as soon as I get rid of the staining.

I'd love to hear your thoughts on the condition of the coil.

Just keep using the heater, I've seen much worse last very long. After the stain removal, it might be wise to use a good sequestering agent, like Sequa-sol or chelating agent, like Metalfree, in the pool. I don't know the chemistry, only that they work differently but do work to help with protecting the heater and keeping the stains from happening again.