SWG and old return pipes

[105ex]

Hello,

I'm interested in adding a Salt Water Chlorine Generator and definitely a newbie in the topic.

I got my pool replastered last year. The company that did the replastering recommended against SWCG for me saying that I'd need to replace the old return pipes that I have for my pool. My pool is about 40 years old and I can see that the PVC pipe coming out of the pump is connected to a galvanized metal pipe that goes to the returns. I'm not sure what's underground, but probably metal all the way to the return openings.

Is there really a problem (e.g. corrosion) with having SWCG inlined without replacing my return pipes with PVC or other types of pipes? If you have URLs that have more descriptions around this, I'd appreciate those pointers.

I've read about stainless steel filters possibly not compatible with SWCG (I have a Pentair Nautilus Stainless Steel DE filter) but didn't find info on the problem(s) with SWCG and metal pipes.

Also, which brand of SWCG system do people recommend? Is the AquaRite system better than the Intellichlor?

I appreciate help with clarifications to any of the above.