Good point Luna. While you can buy bottled RODI (Reverse Osmosis-De Ionised) by the bottle at Jewel or walgreens or something, in the long run you will save money just getting a good unit for yourself. I was buying RODI and Saltwatter at MCF (local fish store) at first, but the $200 or so allows me to avoid constant trips to the store (I make them anyway, but don't have to carry 40/80 lbs of water ever time) and gives me access to the water I need anytime (everything always goes bad when the LFS is closed)