A filter is going to be hooked up to one of the sinks... it's one of those things that makes reverse osmosis water.
I've heard it removes nutrients and stuff, though.
I'm going to be starting a tank with a sand bed and our tap contains something that makes this stuff that looks like brown algae form, and the reverse osmosis thingy takes it out of the water.
My question is... Can plants still grow and Bettas still be happy in that water? I'd prefer to use it if I'm getting a sand bed... that brown stuff is UGLY....