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Tanklets > Blue Staining in Tub

Q: We installed a powered anode rod for hot water odor issues. At the same time we also added an iron filtration system and serviced the existing water softener. Prior to that, the only piece of equipment in the house was a water softener. I can give you more details on the water if need be, no awful stuff. Shortly after installation our customer mentioned that she was getting a blue staining in the tub that is very hard to remove. pH is not an issue at this time... its usually floating about 7.5. My first thought was acidic water and getting copper staining. But I can't find any other issues. Is it possible if the powered rod were to be touching the tank internally we can create an issue? Anyone else every have similar issues??

A: Glad you got around to this. As I said before, if the powered anode were at fault, you'd have blue staining everywhere. My friend Larry Weingarten will see this pretty soon, and he may have some ideas for you. -- Randy

Q1: Thanks Randy. I’m not by any means blaming the rod, I’m just stumped on the cause. Just trying to get my customer done type of answer. Thanks for anybody’s help!!

A1: Blue staining comes from copper pipe being dissolved. So, what's causing it? Three things come to mind.  Low pH is one. Over softened water is another, and erosion corrosion, (like from a 24 hour recirc line) is the third. The National Association of Corrosion Engineers wants you to leave 60-120 ppm of dissolved solids in the water after softening. This doesn't include sodium. Anyway, the possible fixes involve reducing run time if there is a recirc line and leaving more hardness in the water. -- Larry

Q2: There is no low ph. No recirc. Water is soft, I’d have to send a test out to figure sodium content compared to total TDS. But, we have 0-1gpg water almost everywhere I’ve worked with these powered anodes and never a similar issue. I have run into both the pH and the recirc issues, I don’t think this would be a situation here. Outside of blending a little hardness into the water, any other thoughts.
One other thought, the customer says that bleach will clean the staining up, which doesn’t make any sense to me...

A2: One grain is about 18 ppm, so I just round it to 20. That would mean the corrosion folks want 3-6 grains of hardness left in the water to protect the plumbing. So, I think your idea of blending in some un-softened water is a good one. -- Larry (7/19/20)

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