Nature 2 users???

[Vanguard]

CD = corona discharge.  Simply put - "lightning in a box".  

Higher quality systems (like Caldera) use an electrode to do this.  Lower quality systems use a microchip (this may be what you meant by "cell").  

Electrode CD systems produce significantly more ozone, and have a longer life.  

Caldera is far from alone with this.  Sundance Spas offer a choice between the two (I believe Jacuzzi does as well).  Both Bullfrog Spas and Hot Springs Spas use electrode CD systems only.

  
  

Oops.  I did mean CD chip when comparing with UV.  The Cell I refer to with Caldera is the electrode you refer to. There are three types of ozone systems:  CD Cell, CD chip and UV.  Thanks for catching my typo.

[johnnythunders]

If you look under Ebay...
I have bought many nature2s at $15 each when I buy 4 at a time.....
4 for $60 is a well enough investment if you enjoy always going into your spa.
For $15 each I rather have peace of mind,,,,,,,,,No way would  i buy nature2 local
and OVER spend.....JT