RF in shack and ground question
 

Just recently started to use an MFJ artificial ground and comparing it to a
ground rod thru the basement's sump where is always wet.
My antenna is an end fed about 50 feet and I use no more than 30 watts (CW)
While switching between grounds I noticed my field strength meter droped to
almost nothing while using the artificial ground with a wire on the floor,
when switched back to the ground rod the field stregth meter went way up,
all using the same wattage.
So the questions....when the meter reads low does that mean less RF in the
shack and more juice to the antenna?
And a high reading the opposite?
Would love to hear comments/advice.

Thanks...gil