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From the Minelab Knowledge Base Article at https://www.minelab.com/__files/f/254884/KBA_26-1 GPZ 7000 Tips for Better Ground Balance.pdf "A ‘dust iron’ toroid suitable for the HF frequency band (e.g.1–30MHz with an initial permeability of between 6 and 10) has been carefully selected. It is recommended to use this specific Minelab accessory, only. Alternate ferrites may significantly degrade ground balance quality." Note the words "recommended" and "may". Certainly a substitute can be found if someone wanted to make the effort. Like other here though I don't see putting much effort onto it as being worthwhile. Presumably the dam will break at Minelab soon and we will be flooded with ferrite rings.

Fred - My point was not that Mine lab has no need to send the ring to those who have purchased a 7000, and I agree with you that it should be done. I'm just saying that no one should feel like their machine is not working properly because they don't have a ring. Ring or not, the 7000 is a fantastic machine and I have not seen a ground balance problem with it other than the groan in salty ground. No one should feel like their machine is some how limited if they don't yet have a ferrite ring. You can test the ring and see if it makes any noticeable difference for you. In fact I am very interested to hear if prospectors think that it makes a significant difference once they have the rings in hand and have tested them here in the USA.

I have been hunting with the GPZ for quite some time now. So I the am use to the GPZ being noisy it's like running the GPX 4500 very very hot or (maxing out). On this particular day the ground was saturated and as I dug down to recover a target I never hit any dry dirt. The GPZ will find the gold in wet conditions if you listen to what it's telling you through the noise. A proper ground balance and using the ferrite ring is a key part. On this outing I recovered 8.8 DWT and the largest being 5.4 DWT. The quarter ounce piece was at thirteen inches and broad signal. Happy Hunting, Road Dog

Just my opinion, but I have run the GPZ over a wide variety of different types of ground and I am not really sure it's necessary in most US goldfields. If you are running in auto ground balance as many prospectors do, the machine eventually loses the information as new ground data replaces old. The only way to hold the ferrite info is to run in fixed. Honestly the only ground balance issues I have experienced with the 7000 are in salty ground and I have not been back to those spots since getting the ferrite ring.

My recommended GPZ 7000 Ground Balance Method for Salty Saturable soils: 1. If no "Dust Iron" Ferrite, perform a "Walk and Sweep" at start up or after a "Reset Audio and Detection Settings" via Quick Start. I highly recommend you perform this in ground that is not too waa waa (salty) and keep the coil above 30 mm to avoid saturation signals. 2. If you have a "Dust Iron" Ferrite and the area your in is Salty, then perform the Octopus sweep over the Ferrite laying on the ground but limit the speed of the sweep to avoid salt signals and also minimise the amount of sweep distance (tighten the sweep up). 3. Once the above procedure has been performed go into the "Ground Balance Mode" menu and select Manual, this will then lock the GB so that Saturation and Salt signals do not affect the GB after that point. You can configure the USER button to take you directly to the Ground Balance mode menu option to save on time if you like. 4. Go detecting just like you would with a GPX 5000 in Fixed Mode using Fine Gold or Enhance. If you feel the need to ground balance place the "Dust Iron" Ferrite on the ground and perform the Octopus sweep for 3 to 5 seconds or until the unit is quiet (this should be checked regularly). There should be minimal or nil noise over the Ferrite but you need it there once the Quick Trak button is pressed in to get a good GB even if the Ferrite part of the GB is still good. For those without a Ferrite you should do a mini "walk and sweep" with Quick Trak held in, preferably where the salt signal (waa waa noise) is less, keeping the coil above 30mm to avoid Saturation signals. Notes: By using Manual mode you stop the Salt and Saturation signals from interfering with the GB, salt signals can throw the GB out if in tracking mode, this also happens on a GPX 5000 when in Tracking mode. If the detector is exposed to strong Salt and Saturation signals when the Quick Trak button is depressed you could end up with an atypical Ground balance which is not good for effective metal detecting. People need to take into consideration the GPZ's ability to sample very early, due to this it's more aggressive on Salt signals and Saturation signals (probably by a magnitude of 2 or more but not as bad as a VLF), hence operators need to keep that in mind in Alkali or Saturable ground. By using Manual mode and attaining a good GB at start up and maintaining it by regularly checking with the Ferrite during the session you will not have to worry about Salt or Saturation signals affecting the GB. A slower sweep speed has always helped with salt so be prepared to slow down, salt signals vary from ground to ground even over small distances. If unsure it is salt your dealing with just lift the coil to waist height away from your body and listen for a faint to loudish broad signal, if so Salt is present. JP

Here are a few more tips from JP on Minelab's Treasure talk. http://www.minelab.com/usa/treasure-talk/using-the-dust-iron-ferrite-gb-aid-for-the-gpz-7000

Steve is it true one of those little ferrite gizmo's is included with the 7000 or is it an additional item that needs to be ordered. I have read posts that seem to imply one is included. thanks…