Right now to change 20 gallons of water in my tank it takes me close to an hour. I would like to be able to finish this task in a lot shorter time, im a busy guy. The big problem i have is i cannot figure out exactly how much instant ocean salt mix to put in each 5 gal container i have to have a constant 1.023-1.025 sg. Are there any suggestions as to how i can save time?