I've been keeping reef tanks for about 12 years and tried several salts over the years.
Tried IO, Kent, Tropic Marin, Red Sea and now I'm using Seachem Reef Salt. On my third bucket and would have to say it's my favorite so far. Corals really perked up after using it and it seems to be the most balanced of the ones I have tried.
I might try H2Ocean Pro+ http://www.theaquariumsolution.com/?q=node/405, nothing but good things heard so far and it seems to be well balanced like Seachem Reef Salt, with the exception of the dKH being a bit higher with H2Ocean, which is what I like.
i was using tropic marin and every time i was doing 80 gallon water changes my orp dropped from 390 to 215 and ive had some friends notice the same thing dont know why. I did my last water change with H2Ocean from deltec and it went from 390 to 355 i am not sure what this means if anything but just thought i would share.
I've been using IO for over 2 years, but started reefing about 2 months ago. I still have a 5 gallon bucket of IO. Once it's gone I'll probably make the switch to reef crystals. Funny that I can't find it cheaper up here, since IO is made in Mentor Ohio. I get it cheaper online shipped, then buying in a store here.
I went from Oceanpure.....to tropic marin...to tropic marin pro...to D&D H2Ocean I cant but mention that by far the H20cean has been the best salt I have used thus far. I like it and havent seen so much polyp extension from my corals. I like the results.
I've used oceanic for 6 yrs now. I will add buffer if the alk shows up low. Lately I haven;t had to do it. Calcium and mag is always a bit high which I like.
I use Reef Crystals...I was using the Red Sea Coral Pro salt for a while but it was getting to the point that there was always something undisolved in the bottom of the bucket. Not salt, but sand or something. Just didn't trust not to get something bad in the next batch. RC works fine for me. I do a daily 5 gallon change on my tank...65 gallon with a 30 gallon sump.