To best answer your question, you "never" want to search with a negative ground balance while in the "Disc mode". A negative ground balance will cause too much ground noise and the detector will not be stable. In mild to moderate iron mineralization where the ground mineralization does not change much, you can get away with setting the MGB control 1/8 to ¼ turn positive, from the actual ground balance point, without having to stop and readjust the MGB control too often. When you are searching on heavy mineralized sites where the mineralization changes in short distances then it is better to adjust the MGB control ¼ to ½ turn positive (clockwise). By doing this you are "slightly" over compensating for the harsh ground conditions and this allows the detector to maintain better stability. Remember, the X5 has a 10 turn MGB control so a ½ turn positive is not near as critical as it is with detectors that only have a 1.0 turn or 3.75 turn MGB control. Here is a tip to remember: If your detector is noisy while in the MGB mode and is not noisy in the Fixed GB mode at the same location, then your MGB control is set too negative. Please give this a try, as I'm sure it will help over come the situation you described in your original post.

Thanks,

Troy