when it comes to salt they NEVER mix up the same between bags there are some companys that do have a reputation for being very constant and there are companys that are not and what joe schmo from cali mix's his up and and what guy from florida mix's his up at will mostlikly be a bit different and yes the salt would be the reason for the low levels that i get when i mix a fresh batch of saltwater thats aged for atleast a day...could it just be i got a bad batch sure...thats very possible but with all of the money i have been putting into raising calc and mag and the salt togeather its just not worth it and i would like to try something else.