Salt water generators voiding the AGP warranty

[chem geek]

Some, but not all, of the AGP manufacturers use inferior materials. They will corrode faster under conditions of higher electrical conductivity and chloride concentration as is the case with saltwater chlorine generator pools typically using 3000 ppm salt. Most commonly, the problems are seen with inferior stainless steel (or zinc-coated -- i.e. galvanized) screws on some parts such as skimmer openings. However, some people have simply replaced such screws with more appropriate ones and then had no problem. Some examples are here, here (with photos of some rusted bolts here) and here.

Inferior materials are going to have problems even in pools with lower salt levels though will take longer for such problems to develop, but any material "on the edge" can corrode more quickly at higher salt levels. With stainless steel in particular, higher chloride levels interfere with the reformation of the passivity layer so if the material isn't good enough and the chloride level is high enough, then one can inhibit the passivity layer formation faster than it can form at which point one gets runaway corrosion as raw steel becomes exposed. This was discussed previously on this forum such as in this post. Also, when dissimilar metals are used, one can get galvanic corrosion which occurs faster under conditions of higher electrical conductivity (which is very roughly proportional to the salt level as the added sodium chloride salt is the largest component of all ions in the water).

So while the "root cause" may be use of inferior materials, it would be incorrect to imply that the higher salt levels are not a factor. When there is more than one contributing factor, one needs to look at them all together as a system.