No, don't use any ammonia or nitrite removers; they may lock up the toxins in a form that the bacteria can't use, causing the bacteria to starve. More water changes are the best remedy; at least your tank's only small!
Well, they must be worth a try at any rate!
I'd seriously consider doing another water change though; I'm really worried about that nitrite reading. It's perfectly ok to use water from the hot tap or from the kettle to warm the water if you need to.
Perhaps use boiled water from the kettle, just to be on the safe side; although the white stuff is probably just calcium/limescale![]()