Hi! I have a ghost knife and I use bottled water along with some tap water to balance out the nitrate, nitrite, hardness, ph and all that stuff. Bottled water works great. Use distilled bottled water. My ghost knife loves it a lot. When I purched him they said that he would hide a lot. Well I have a bubble screen and he loves to swim in it. They do not like the light a lot. When I turn on the bright light he usually swims away. He also likes to eat blood worms. Hope this helps.
~Kim~