Followed directions and used 2 cans Mag-Erad manufacured by Tri Brothers Chemical Corp. and recommended by A.O. Smith for my 40 gallon gas water heater. Cost was $84 with S&H. No change to noise when water being heated. I called Tri-Brothers, was told may need add'l treatment, type of water/anode causing problem, etc. etc. etc. I called A.O. Smith about refund because of results and reply- can't issue refund because product has been used(???) I should have applied $84 to new water heater.<br />
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