Can I just put a bunch of magnesium in the tank instead of an anode?

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optimistic realist

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Can anyone think of a reason why it wouldn't work if I put a bunch of magnesium into the bottom of the hot water tank to act as a sacrificial anode? I may not be able to replace the anode the normal way. The only problem I could think of is, possibly that the magnesium sitting on the bottom of a lined tank may not corrode quickly due to not being grounded... but I doubt not being grounded will prevent the magnesium from corroding. I'm thinking of jamming as much as I can find into the tank. Anyone think of any problems I would have if I did this? Also, any ideas where I can get some magnesium for this?

Thanks
 
The anode needs to be connected to the metal it is protecting. If there isn’t a circuit it doesn’t work.
 
Geofd said:
there are anode rods that come in links so you can fit them into the tank...you will have to search it …...
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I don't want to use a proper anode. I just want to jam some bits of magnesium in the tank instead. I suppose that I could cut up a proper anode but it would be cheaper just to find some magnesium.
 
FishScreener said:
The anode needs to be connected to the metal it is protecting. If there isn’t a circuit it doesn’t work.
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You are saying that the magnesium that I drop into the tank won't corrode otherwise? You might be right but I don't see why you would be. Possibly my idea would be less efficient IDK, but that may be overcame by using more material. Oxidization should occur regardless.
 
For the sacrificial anode to be the anode, it has to be electrically connected to the metal it is being sacrificed to protect, the cathode. If it isn’t, all you have is two metals corroding.

The anode corrodes at a faster rate than normal, and corrodes for both of them.
 
FishScreener said:
The magnesium will still corrode, but so will the steel of the tank.
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How do you figure? There is a finite amount of free oxygen in the tank. This limited O2 should be drawn to the magnesium, saving the tank (and element). The water should be an adequate electrolyte to make this kind of a circuit. ATM I am more concerned with my element disintegrating in 1 month than my tank. I am supposing that my 6 year old tank is still being protected by its lining. If I had used a normal anode, the anode would not be in direct contact with the element anyway, so it wouldn't be any better at protecting it than what I propose. At the least, every bit that the magnesium corrodes would be that much less than anything else does, given the finite oxygen. I think, but I'm not a chemist.
 
It’s part of a water system. Fresh oxygen is brought in any time you bring in new water. And, what makes you think all the corrosion is on the inside?

I’ve never had an element fail due to corrosion. Idiots turning on the water heater before it refills: Lots of those, but never corrosion. The outer sheath of elements is made of high nickel steel, or cupronickel steel. Both of which have really low corrosion potentials.

The sacrificial anode is to protect the tank. It is bonded to tank by being threaded into it.

And, I’m not a chemist either. I’m just a dumb ol engineer, with a minor in physics, who had a corrosion engineering class, nearly thirty years ago.
 
It is not just about oxygen. It is about electrons and the Periodic Table of the Elements. Electolytes in the water react with the iron to create a very tiny electric current that removes electrons from the iron, changing its state and combining with dissolved oxygen to create iron oxide, or rust. Magnesium (Mg) is a metal that gives up (sacrifices) its electrons easier than does Iron (Fe).
As noted above, it must be electrically connected to the iron or it won't protect the iron.
 
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Also, I imagine the magnesium would just lie in the bottom of the tank, insulated from the steel by the glass liner. So, no electrical connection, no anode/cathode relationship, no protection.
 
I stopped reading a few replies back. The plumbing code is there to protect you. They write codes usually after an accident to try to insure that you are protected from history repeating itself. That said. If we don’t hear from you after you attempt to do it your way. We know why.
 
Mikey said:
Also, I imagine the magnesium would just lie in the bottom of the tank, insulated from the steel by the glass liner. So, no electrical connection, no anode/cathode relationship, no protection.
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The water and minerals therein would provide the electron pathway needed for the anode / cathode relationship. The heating element is insulated from the tank, yet it still corrodes to failure within one month. It corrodes due to the electrolyte allowing electron transfer... same way the magnesium rods will corrode in the bottom of the tank. I think.
 
Ok do what ya want since your the professional cause apparently the plumbers here dont no ****. idiot
 
fixitron said:
It is not just about oxygen. It is about electrons and the Periodic Table of the Elements. Electolytes in the water react with the iron to create a very tiny electric current that removes electrons from the iron, changing its state and combining with dissolved oxygen to create iron oxide, or rust. Magnesium (Mg) is a metal that gives up (sacrifices) its electrons easier than does Iron (Fe).
As noted above, it must be electrically connected to the iron or it won't protect the iron.
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It is mostly about oxygen... hence oxidization .
 
FishScreener said:
It’s part of a water system. Fresh oxygen is brought in any time you bring in new water. And, what makes you think all the corrosion is on the inside?

I’ve never had an element fail due to corrosion. Idiots turning on the water heater before it refills: Lots of those, but never corrosion. The outer sheath of elements is made of high nickel steel, or cupronickel steel. Both of which have really low corrosion potentials.

The sacrificial anode is to protect the tank. It is bonded to tank by being threaded into it.

And, I’m not a chemist either. I’m just a dumb ol engineer, with a minor in physics, who had a corrosion engineering class, nearly thirty years ago.
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Of course, oxygen is brought in with the fresh water... this doesn't change things... dissolved oxygen is still finite. Not sure what you mean by, "what makes you think all the corrosion is on the inside". Really puzzled about what you say about never had an element fail because of corrosion... My second element (stainless with copper inside) was significantly disintegrated inside of 3-5 weeks, literally. Once I find the receipt I'm going to have a fun time making the clerk believe I just bought it! Bottom line is, it sounds like you figure that the electrolyte is not enough to create an anode/cathode circuit. You could be right. I shall know the answer if I need to replace the stainless element again in a month or not.
 
journeyman said:
Ok do what ya want since your the professional cause apparently the plumbers here dont no ****. idiot
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I don't expect most plumbers to know for sure, and I DO expect to hear from mostly naysayers from "go" regardless of the issue. Believe me because "I'm a professional", or "I'm a physicist" doesn't really fly. If you are such an expert, you should be cogent.
 
This is obviously NOT a question that a plumber is expected to know the answer to. I see it as a request of opinions and discussion only.
 
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