Electric current/voltage in Sump's water?

[MuddyWaters]

Is it normal to have a small amount of stray current / voltage in the Sump's water (where all the electrical equipment goes)? I've been researching and can't get a definitive idea if this is normal or not. Testing with a voltmeter shows approx 1 to 1.2 volts of current in the sump water (tank is zero thankfully); sump contains 1 Eheim retrun pump, 2 heaters, 1 SWC Protein skimmer. I've read about grounding probes etc. as well as the fact that they do not solve the problem, just ground out the electricity. In all cases it is suggested to find the 'bad' piece of equipment and replace; but in my case nothing appear 'bad', just each piece seems to add .2 to .4 volts to the final total, so it appears to be trace leakage from each.

I don't want to just add a grounding probe without understanding the cause or if this is normal. Do I really need a ground with this small amout? Any thoughts, conversations, suggestions would be appreciated.