I guess thats true. My return pump is marketed with "no copper components" so im hoping im safe there.I agree about the MP40's, but I like my DC return pump to be on a GFCI. If my return pump develops a crack it can release copper and toxins into the water of my system. It may continue to run for weeks or longer in that condition. I want it to trip immediately to let me know it has an issue. For me, a GFCI/ground probe combination is just as much about protecting my reef as it is about protecting me.
It wont help when the mp40 wetside cracks its ceramic shaft and exposes the rusty shaft though
Ive ran my vortechs for years in this condition without knowing.
Luckly no elevated values on icp.