[Delphinus]

I test for Ca, Alk and Mg for every new BATCH of salt (new bucket or new bag). After that the first water is made, I don't bother with it again (ie. don't test for every water change).

I have been burned far too often by being caught unawares that a salt is not living up to its credo for params. The irony is the more expensive salts have always been the worst offenders too. Just because you pay more doesn't give you an assured QA process, apparently (and I love how it always gets turned around on you so that it's the "users" fault that a salt has no Mg or Alk because they didn't "mix the salt before mixing the water". I think that's totally absurd, but yeah, I guess you have to do it since you can't rely on the salt makers to adequately prepare their product before they send it to market). Although I would go so far to suggest that the times I noticed that Alk was woefully low, or dangerously high, or Mg was half the advertised claim, that pre-use mixing the salt didn't help - the problem was the salt itself.

So, I don't bother with premium salts anymore. If I have to dose Ca, Alk and/or Mg into a salt I figure I might as well save a few bucks because the price of chems is far less than the increased premium price on the salt itself. So I use IO, I accept that I'll have subpar Ca, Alk and Mg, so I dose accordingly for each new batch of salt. (The surprising thing is these numbers are usually not as bad as you'd think, to boot.) The nice thing is that once I know how much a batch needs for one makeup bucket, I know how much to add for the next water change.

But it does mean I *have* to test each new bag or bucket.