Make very certain the odor you have is not glycol. With engine heat exchanger systems it is imperative that you use low/no tox coolant as even a minute amount of automotive antifreeze can kill you. The less lethal possibility is a large build up of minerals in your water heater. Shock treatment as cam described works great for that algae smell / taste. I use chlorine year round at ppm levels compatible with our longevity.
I also have stainless tanks that have been unaffected by this treatment for a little over 35 years. Have fun!