You shouldn't have any leaking voltage.
Get a normal power strip and plug your devices into that and see if you have an issue with stray voltage. Most likely it will be one of the devices that is causing your problem. Unplug the devices one by one until you find the offending device. Be sure to test all the devices, one at a time, because it's possible that there is more than one bad device.
If you don't find a bad device, plug in the reefkeeper PC4 with no other devices, and see if you have a stray voltage issue. If you do the problem is with the reefkeeper PC4. You can try disconnecting the controller cable from the power strip and see if that is a factor, but I don't think it will be.
Most likely you'll have found the problem by now, but if you didn't, try this. Move the device plugs, one at a time, from the normal powerstrip to the reefkeeper PC4, and see if you now have a stray voltage issue.
Very Important Note - Always test for stray voltages with a voltmeter. DO NOT TEST BY PUTTING YOU HAND OR OTHER BODY PARTS IN THE SYSTEM. Electricity and water can be lethal.