Bittering addition amounts for ipa

Silly question - but is there a particular kind / brand of epsom salt to use for water adjustments?  Is the laxative one ok, lol

Yeah, that’s the one.  The USP epsom salt from the pharmacy.  If it’s labelled as a laxative (as well as a bath soak etc.) it’s pure and safe for food use.  If it’s just labelled for bathing or whatever, don’t brew with it.