That's pretty close to what I am looking for. I'm looking for 7.5 dKH ideally. I've got a few buckets of NeoMarine that say they mix up at that, but I haven't tried them yet.
I bought some IO while it was on sale on Black friday because I wanted a salt with lower Mg levels so I could load it with Kent tech M (not that my bryopsis cares about it.). It's alkalinity consistently mixes up at 10.64 dKH (I've mixed 240 gallons so far in two batches). I had to burn the excess off with HCl (not a big deal, but I would rather not have to do that on a regular basis).
I had been using Red Sea Blue bucket, but it's a little higher on the alk than Ideally want and tends to be consistently low in Mg. Not a big deal but it would be nice to find one that was consistently close to what I am looking for. That way I can mix 100-125gallon batches,test and not have to make major adjustments. I'm getting ready to set up constant automatic waterchanges to the display tank, so in the spirit of simplification, I'd like to find a salt that I can mostly be happy with the parameters.
I think in part because of this thread I have it narrowed down to NeoMarine and now Tropic Marin Pro. I think next salt purchase I will give the Tropic Marin a try. I have 3 buckets of NeoMarine to get through after 3 boxes of IO... I could let the tank decide.... I'll let you know in roughly 99 weeks what the tank decides it likes the best between the three.