Thanks for the explanation. You made a good point about the A/C pump. I forgot all about that. So there are actually a few places where the zink “meets” the shore ground. I’m in a marina in St. Martin and connected to the shore power for most of the time. In this position I’ve calculated my anodes to last about 6 months before left at 40% weight and replacement becomes required.
So It seems I’m not playing to be a huge battery in the marina too much.
I will verify if the bonding connection to the watermaker is working as supposed and make sure the leaks are rectified. That is all I can do I think for now.
I did have a nice time taking off the caps of the membrane vessels by the way. In the end I drilled a 3 holes in the side of the caps (120 degrees apart), tapped a thread in it and put a bolt in. I then could use hammer and screwdriver to gently tap out the caps by using the side of the bolt-head as hit point.
Hopefully next week the whole thing will be back on its feet again.