I have been researching water softeners in the hope that I choose the best one for the money. Having said that I noticed that many companies on the net have different opinions on when to use a gravel bed in your softener. It seems to me that anything over 10 inches dia. resin tank most recommend having a gravel base however I have found answers to this question from anything over 10 inches to not needed at all in residential applications. It sounds like a bunch of opinions without facts. Is there a factual answer to the question or anyone have another opinion?
Anwser: Easy question to answer – anytime a standard down-flow design water softener is used, regardless of tank size – you always need a gravel bed. The layer of gravel in the bottom of the tank allows for good distribution of water throughout the resin bed during normal service, and aids in backwashing (cleaning and re-organizing the bed) during regeneration.
However, there is an exception to this rule – this is when the unit is equipped with a Turbulator (GE/Autotrol name) or Tornado (Fleck/Pentair name). Gravel is never used when the system contains a turbulator, as the gravel particle size is too large, and would cause turbulator failure. Turbulators physically move the resin from the bottom of the bed to the top, stirring up the bed to increase sediment removal and water softener efficiency. Using a water-stream compression device, they propel resin beads at high speed to the top of the resin bed, then allow them to settle back to the bottom. Small sediment that may have accumulated in the bed (like dirt or iron) is scrubbed from the resin beads and washed to the drain. When a turbulator is used, it is not necessary to have the gravel function as a distribution bed, as the resin bed is constantly turned over and reclassified anyway during regeneration, resulting in good flow distribution.
So basically, if someone is trying to sell a softener without gravel, they are simply trying to save money in shipping (gravel is heavy). When a turbulator is not used, gravel is always required. If you look at some of the softeners we offer on our site, you will note that all systems 48,000 grain (10 inch diameter tanks) and smaller are equipped at no additional charge with Turbulators – 64,000 grain and larger are supplied with high flow risers & gravel underbed – Turbulators do not function at peak efficiency when used in tank diameters larger than 10 inchs.