Wiring advice/help needed (voltage in tank)

[GoFish]

So just finished doing some tests. Followed THIS link checking my GFCI, and got the same results so it must be installed correctly.

Not sure what i was doing wrong last night but i tested the Coralife powerbar again with a lot less clutter around and was able to get proper readings, no issue with the powerbar. SORRY for the confusion, it puts out 120v 'ish. it has these turning child protectors on it and is real pain in the a$$ to get these little voltmeter probes in there/ got 40 a few more times and figured out the angle

First, with nothing plugged in. Positive probe in tank and negative probe of voltmeter in ground on socket still reads 2.7v, I put the ground probe in the water and it drops to 0, i figure with the probe it would release any stray voltage from the water, but nope, no matter how many times the rid-volt goes into the water it jumps back to 2.7, still with nothing plugged in. Tank water will not read 0 without Rid-volt

TEST #1
So + in tank, - in ground on GFCI (This time i plug in each device and then unplug and move to the next one)
2.7v w/nothing
T5 Lights = 4.6
Koralia = 15
Aquaclear = 9.5
Skimmer = 20.6
Heater = 22.0

Test #2
This time, same as above but the Rid-volt is now plugged in and in the tank.
0.0 w/ nothing
T5 Lights = 0.0
Koralia = 0.0
Aquaclear = 0.0
Skimmer = 0.0
Heater = 0.0

Now i try i different circuit from the kitchen via an extension cord

Test #3
So + in tank, - in ground on powerbar plugged into extension cord ( I only used the powerbar on this test cause i needed a ground from that circuit to use. Theres a 50 foot power cord being used now so that may explain the lower numbers from test #1
0.7v w/nothing
T5 Lights = 2.7
Koralia = 10.7
Aquaclear = 7.1
Skimmer = 18.2
Heater = 20.4

Test #4
Same as test #3 bu this time on the other circuit
0.0 w/ nothing
T5 Lights = 0.0
Koralia = 0.0
Aquaclear = 0.0
Skimmer = 0.0
Heater = 0.0

hmmm, all my equipment appears to be faulty now?? Is it at all possible that my un-grounded T5 issue from 2 weeks ago could have caused other equipment to slowly break down the ability to not release stray voltage?