Vinegar to clean water system..How and how much?

Full strength on the vinegar or get a commercially mfg scale/calcium remover if the scale is causing issues.
Separate note on hard water spots on paint or gelcoat, vinegar /water or vinegar/water/spray wax mix does wonders on baked on water spots. I have a black gel coat boat that shows water spots froma mile away, lol. There are commercial products but IMO vinegar works about as good as any of the high dollar water spot removers. It's standard issue for wiping down boats.