Question on 603 expansion tank
 

I just got my replacement tank from fastlane (old one cracked - 20 yr old plastic) and there seems to be a small white block in one of the chambers. I am familiar with chemistry and I was wondering if anyone knows if this is an electrolysis block IE: sacrificial zinc, etc. Having seen how these can save an ocean going boat and its engine, I like the idea.

That's a silica pack used to control corrosion.

Good to hear.
 

I have seen the small zinc block and the milky solution for the same purpose. I'm happy to learn someone somewhere is thinking one step ahead.