a little stoned, but totally confused PPM//EC/CF

What gives? I just bought a truncheon nutrient meter and there are 4 different scales to select from EC/CF/PPM X 500 and PPM X 700
Could someone please break down what these are and how they differ?

When using the ppm calculator on the GH web page:

General Hydroponics Flora Nutrient PPM Calculator

You have to multiply the final reading by 2.5

Is the final ppm reading (After being multiplied by 2.5) equivalent to the ppm X 500 or the ppm X 700 scale on the meter? (It does not specify on their page)

If the reading IS for the X 700 scale (which I believe it to be)

Would the reading NOT multiplied by 2.5 correspond to the X 500 scale?

I kinda understand the Electrical Conductivity, but don't have a clue what the CF scale is.

Well, Most people use the 700 scale.

Personly I just use the EC Value. that way I can't go wrong.

It may seem confusing at first but the great thign about these meters is you can see all 4 scales at the same time. handy when your tring to understand what people are talking about online.

Had a quick look at that link. I would asoom, 700 scale. Better to asoom the higher one any way.

There are plenty of fourmlars for Those nutes online if you search.
Best of luck with your grow.