I have always used Reef Crystals mostly because it is easy to get. I see all kinds of other brands in Coral magazine and wonder if they are better? Do you mix your saltwater and then just pour into the tank right away? It is recommended that you make it the night before and let it really mix and dissolve before you pour into the tank. This allows it to get at least to room temp before pouring in. 10% won't bother tank much but freshly mixed salt and cold water hitting a Duncan might cause it to close up for a little. I have 15 gallons of saltwater always available and heated to the temp in my display. I also have a circulation pump to keep it mixed well. You can always throw and old power head in a five gallon bucket too!