Lemons or Melons: The Ground Balance Number

As soon as you buy a metal detector, you begin to hear about Ground Balancing. Ground balancing is the thing you do to your metal detector so that it ignores the minerals that are ever-present in the soil and only generates a tone when there is a metal object under the coil.

When you ground balance many of the detectors out there, especially the ones with some kind of digital screen, you get a number. I, like many others I am sure, thought that that number told me how bad the soil was (i.e. how much iron there was mixed in with the dirt). Turns out I was wrong.

Imagine if you will, that your detector is a fruit detector. Now let’s say you want to find strawberries for your strawberry shortcakes. However, the strawberries are mixed with a bunch of lemons and melons (same letters in different order give you different fruit. Cool eh?). You want your detector to ignore the lemons and the melons and only beep when there are strawberries afoot. So you ground balance the machine to ignore the lemons and the melons. Simple.

But what does the number mean? The number tells you what you are balancing out: lemons or melons. That’s it.

Now, you still don’t know how many lemons or how many melons there are in the ground. You, at this point, only know what fruit the machine is ignoring, not how much the concentration of either there is.

To get back to dirt and metals, in our hobby we are concerned mainly with two minerals to ignore: iron and salt. Also, as with everything else in life, things are not so black and white. In reality, our soil is made up of a mixture of both. So the Ground Balance number is really a kind of an index.
I suspect that this index is different for each brand and each model of detector out there. To my knowledge, no maker of detectors has ever put out a chart detailing what specifically each number means. The way I understand it today is that the higher the number the more iron you have and the lower the number the more salt you have.Now, many detectors out there have a little bar somewhere on the screen that tells you how much iron or salt there is in the ground.

My XP Deus metal detector has a little bar. The White’s Spectra V3i had a whole slew of tools to tell you exactly what kind of mineral you had, what percentages of each iron and salt you had and how much of each.

So to summarize; the ground balance number tells you what kind of minerals exist in the soil and the little bar (if you have one) tells you how much of each mineral you have. Don’t ask for more detail than this. The engineers who design metal detectors took Advanced Calculus and Differential Equations and they do all the hard work for us. I only got as far as College Algebra.

There; clear as mud.

Thank you for looking!

Tags: metal detecting theory