I am AMAZED with this salt. I've had reef tanks for over 20 years and even own a reef shop. I got my 1st box about 2 months ago and sent in a sample to a lab for testing along with the 3 other "salts" I was using in my shop. I was stunned at the results of all 4. The ESV was the best. Ammonia-0.02, Nitrite-0.006, Nitrate-0.3, Phosphate-0.01, Silica-0.5, Potassium-636, Calcium-582, Boron-4.0, Molybdenum-0.3, Strontium-8.7, Magnesium-1688, Iodine-0.05, Copper-0.00, Alkalinity-3.41. It mixes in RO/DI water crystal clear. No white residue on the side of barrel or gunk on the bottom. Mixed in minutes. No waiting 2 or 3 days to use. I'm switching to using this salt exclusively for my shop tanks, for my shelves and for my own tanks. I won't use any other salt again. Mix the whole box or just a gallon. I can't say enough about how thrilled I am with this salt. I found NO cons to it at all. Very impressed.