In the past 2 years I have used 3 different brands of salt. Bottom line is I don't trust any of the big 3 (Ca, Alk, Mg) to be spot on and I test my NSW a lot more than I used to.
Tropic Marin (not pro) is what I'm currently using. I used TM Pro many years ago with great success and not really sure why I strayed away from this brand other than price. Calcium and Magnesium have tested low for me on one bucket but I can report more as I have two unopened buckets ready to be used in the near future.
Alkalinity is in a very good range which is most important for me.
Red Sea Blue Bucket. This salt has also been just fine for me but again has been pretty low in Magnesium and Calcium and needs to be supplemented.
Alkalinity is in a very good range which is most important for me.
Red Sea Pro. After a couple year break from the hobby (many years ago) I stupidly used this salt without researching.
Alkalinity is way too high to be any use to me.
Aquaforest Probiotic and Reef Salt. As
@GoVols has said the included sheet should not be trusted and, if anything, will give you a false sense of confidence. This salt mixes the quickest of any salts but unfortunately is the
most hygroscopic (by a long shot!). That means if you have any puncture in the bag (this happened during shipping with about 50% of the salt I ordered) this salt will turn to a giant rock very quickly. The reason I stopped using it was due to coral issues and potentially acro paranoia and reported "bad" batches.