I have a 75 gallon tank. In 2 weeks I need to do a 75% water change after treating flukes with prazipro in my display tank. How do I do this, I don't have the space or bins to mix that much water ahead of time. So what do I need to do, to do this large of a water change safely for the fish. Do you have any ideas or tips? How do you go about large water changes