The ground missing isn't the problem. Even with it missing, the 120V shouldn't be coming in contact with the water. The reason you get shocked is because you create a path to ground when you touch the water. Your fish are ok because they are not creating a path to ground when they are swimming around.
If you have a voltmeter, you can put one prong into the ground of an outlet and touch the other to the water. Then, try unplugging one item at a time and see which one stops the electricity when its unplugged. If you don't have a voltmeter, you can always just touch the water and see when the shocking stops. It's only 120V, but do so at your own risk.
The ground prong on your power strip only works if the equipment plugged into it has a ground prong on it, which most of my equipment doesn't have one.
I have 2 800 watt titanium heaters
This has happened to 100% of the titanium heaters I have owned. I hate those heaters. Some swear by them but considering I am 0 for 3 on heaters and all shock when they fail I refuse to use them anymore.
This sucks reason i got them was bc i thought they would be safer then glass heaters.....they were the catalina ones with temp control.
What would u sugest to use on a 600?
I use the Fluval e-series 300w. I just use multiple (redundancy is a good thing with heaters anyway). Ray safe and far more reliable IMO.
All of the equipment that was hooked up into that surge protector had a ground prong
2 800 watts titanium heaters and 1 laguna max flow 2900
Yours may not have it bc ur runing a smaller tank with smaller eqipment.......majority of equipment has a ground prong