ya, just making some water with Ca and Mg in it. Didnt think about not being dosed, would be that high?

Second for raising your calcium over the next couple days. Will offset the Alk a bit but if nothing is stressed there is no need to do large scale water changes. IO salt has high Alk at 10-12 DKH anyways.

Double check with another kit before changing anything. The chances of it really being that high are pretty slim unless you were really screwing around with something. I would expect your pH to also be high if it were really 16dkh and things would not be looking normal.

I had a Salifert Alk kit that seemed okay most of the time but the first time I tried it on a freshly mixed batch of IO I had the same result. Carefully double checking the kit did show that it was reading ~1.5 dkh high compared to others but I never figured out why it measured that one batch at 16.

Is this water really fresh? I've heard this before with IO salt, freshly mixed.

Water is FRESH, as in 6 days old.

6 days old isn't fresh it is aged new water... the problem with IO is if you measure it befor it is totaly desolved.. once it is a day old I have always gotten true readings. but there were thoes bad buckets about 7 years ago which had huge alk and wipped out tanks, but seeing your readings thats not the issue.

you high alk is depressing you Ca level and because your Mg is a tad on the low side it is making it hard for your Ca to come up to offset your alk. I would sugest raising your Mg to 1350 befor you add Ca. you will notice as you raise your Mg you Ca will increase a bit also and your alk may drop on its own as the Ca comes up. once you have your Mg at 1350 wait a couple days for everything to stabalize and raise your Ca to about 400. then check your alk and there is a good chance it will now be well under 13.

Steve

OK thx. Just added more CA and Mg last night LOL. Hopefully not to much CA. But I'll check later today.