Just wondering ... is it OK to mix two different types of salt together? I have about 8 gallons of Seachem salt water mix left over from a previous top-off on my mini-reef and need to do a water change on my main tank today using Instant Ocean salt mix. Can I add the Seachem with the Instant Ocean and put it in my main tank? This will save me about six hours of waiting to make RO/DI water. Thanks in advance.