Rust growth on top of 5 year old water heater

[Random]

Rheem water heater. Pipes had leaked onto the top, were replaced. Now I'd like to arrest the rust spreading. Plumber suggested Coca-Cola, which I think dissolves it, doesn't arrest & seal it. An acquaintance suggested Ospho. Certainly the difference in Cost is measurable. Is it worth the $20 to buy Ospho, or is there a cheaper but as effective treatment/sealant?

 

[breplum]

Rust will not spread nor be a problem once you solve your moisture source problem. Likely condensation from your flue. Double wall pipe in unconditioned space is normal. We often get away with single wall, but it tends to cause moisture like you have.
Also, flex connector leak if applicable.

 

[Random]

Rust will not spread nor be a problem once you solve your moisture source problem. Likely condensation from your flue. Double wall pipe in unconditioned space is normal. We often get away with single wall, but it tends to cause moisture like you have.
Also, flex connector leak if applicable.

Problem solved when leaking copper pipes replaced. The water closet is located outdoors w/ a louver door so gets some air flow. My experience has been that rust will continue and I am concerned about the integrity of the metal on the w/h top, the rust eating through.

 

[Twowaxhack]

The rust on the shell is not that much of a concern other than cosmetic. The tank is what’s going to rust out, eventually.

 

[Random]

The rust on the shell is not that much of a concern other than cosmetic. The tank is what’s going to rust out, eventually.

Really? So the "shell's" condition won't eventually compromise the tank itself ( or the condition of anything in contact with the rust)?

 

[Twowaxhack]

Really? So the "shell's" condition won't eventually compromise the tank itself ( or the condition of anything in contact with the rust)?

If you stopped the leak then that’s good enough. The outer shells only job is to hold the insulation in place and make it look pretty.

 

[Random]

If you stopped the leak then that’s good enough. The outer shells only job is to hold the insulation in place and make it look pretty.

Thanks!