Long after I had established my tank, I started doing my water changes with pre-mixed RO/DI salt water from a local pet store. I was doing weekly (or bi-weekly) water changes of 10 gallons for my 72-gallon. I had two plastic kerosene jugs that I bought from Home Depot to transport my water. I figured, the time and money it ended up saving was worth lugging around two 5-gallon jugs to do my water changes with. Plus I was in an apartment that I didn't have the luxury (or space) of rigging up my own RO/DI unit, let alone the cash to buy such an investment and its replacement parts.