Just got zapped hard!

[FishyFishy!]

So im holding some good live rock for my new build. Lots of life etc. 2 tanks with a powerhead, a heater and a small HOB filter.

Today I went to touch the water (as I always do to make sure that my thermometers are accurate). And it felt like someone punched me in the chest! Got it bad enough to knock me on my a$$.

So im thinking heaters, as these are the common culperits. Im kind of scared to test my theory though. Dont really want to replace the heater and try it again lol. How do I test for voltage without killing myself?

And the big question...now that I know this is happening....is everything dead in the rock now? Or would the current not harm bacteria etc?. I havent gone back out to look for pods etc.