You didn't say if you were using auto or lock. I don't know if you have a V3 or V3i? Lock works OK if your ground doesn't change much but if not auto is in order. You could try adjusting your tracking speed.
Everything to which the V3 responds (with sufficient strength), generates a VDI number. The ground mineralization is no exception. When the V3 is ground-balanced properly, the V3 sniffs out the grounds VDI number and sets the circuitry to lose sensitivity to targets with that VDI number. It never stops, it's always tracking. All we have control of is how fast or slow it takes to get to that balance point. The speed changes how long it will take to get to the new ground level. If you are seeing it track up as much as track down, then it's probably staying pretty consistent. The speed changes how long it will take to get to the new ground level.
If you have slowly changing ground, setting your track speed slower would keep it more stable. If you have ground that's changing all over the place, set it up for a faster speed. If you are going to use an offset, set it first. Whenever you make an adjustment, the LAST thing you do is Ground Balance. The detector "sees" the composite result of all the settings, so you should ground balance to the setup you're going to run. You can go too far either way with your tracking.
a. Too slow and your machine will drop out (go silent)
b. Too fast and your machine will try to accommodate every little change and you'll get "overshoot"
The "optimum" tracking speed is one that just keeps your threshold constant as you're hunting .
To check ground balance go into pinpoint and then lower the coil close to the ground. If you don't hear much audio change) then it's probably just fine. If you are hearing too much audio change you probably need to adjust your speed.