If your water heater is old you may need a new Sacrificial Rod. It screws in at the top of the tank and protects a water heater tank from corrosion. See one here → http://amzn.to/2iFrEnn
I think the frequency of water heater flushes should depend on your local water supply. If the water that flows into your home is full of minerals and particles, it’s going to settle in your tank and build up quicker.
A viewer pointed out to me the sticker on the tank: “EverKleen Self-Cleaning Water Heater” Can you believe it? I didn’t even notice! Too funny! Well it does show how well it actually works!
Rheem – Guardian Gas Water Heater