What are teses tiny rust-like stains?

[poolbee]

I said as I recall. I have been reading up on so many different things I am probably confused. That's why I come here to seek advise, so I don't have to trial and error it. I am definitely not giving out any advise as I am absolutely no expert. I think I may have honed in on the Blue Stuff as it says it is for pools with heaters and dismissed the Purple as not because it doesn't specifically say it is. I guess I assumed and you know what they say about assuming...
Anyway, I do have a SWG so the Purple Stuff would be the best bet for me?

[waterbear]

I said as I recall. I have been reading up on so many different things I am probably confused. That's why I come here to seek advise, so I don't have to trial and error it. I am definitely not giving out any advise as I am absolutely no expert. I think I may have honed in on the Blue Stuff as it says it is for pools with heaters and dismissed the Purple as not because it doesn't specifically say it is. I guess I assumed and you know what they say about assuming...
Anyway, I do have a SWG so the Purple Stuff would be the best bet for me?

The reason the Blue Stuff says it's for pools with heaters is that most heat exchangers in heaters are copper and the Blue Stuff has a high chelation index for copper. The purple stuff is for pools with high TDS which include all saltwater pools.