OinKY wrote:No harm in grounding and running all equipment through a GFI outlet though....always better safe than sorry.
I actually ground my large tank because anytime there is moving water, there is a potential for an electrical charge. The way to test for any such voltages is to take a volt meter, set to the AC scale and insert the Positive probe into the tank water and the negative probe into the ground lug of your standard wall outlet. Personally I have my tanks on dedicated GFCI wall outlets, with surge protectors between appliances and outlet. I use just made something similar to the ground probe that sells for typically like $20 and it didn't really cost me anything. I just took some thin stainless steel wire and wrapped it around one of my filter inlet tubes and where it came out of the water, I connected it to standard, stranded wire and ran that to connect into the ground lug of your wall outlet. The way to test if it is doing its job is after you setup the ground probe, do the voltage test (mentioned above) again and it should eliminate any traces of voltages.