I've used several from IO, Coralife......I stuck with ReefCrystals with great success, no problems with dissolving or levels......Tried Seachem found harder to dissolve and had a couple bad buckets so quit that.....Tried Oceanic, did disolve quickly, but weren't crazy about the consitency of their levels......Never had the algae issues people have claimed though.....Tried Tropic Marin Pro, and have been rather pleased with the results.....I'm torn between the ReefCrystals and Tropic Marin though.......I've heard issues in regards to the Tropic Marin Pro lately and waiting to see the outcome......I've heard that Hawaiin Tropic has really good readings than the other salts.......