Given that i do not have any pre mixed up supply of water, what is the easiest way to go about doing a 10 gallon or so change on a 75 gallon tank. I keep my salinity at about 1.024, and temp about 78 in my tank. How do i match this with the water I am putting in, and whats the easiest process for this. I was thinking in my head of buying 10 gallons of water from the acme and adding the salt to each one at a time etc and taking 10 gallons out...lol, sounds really stupid..has to be a better way.