new tank problems

Hi there everyone,

I'm having a problem and looking for some advice, I'm hoping it fairly
basic as this is my first tank.

I've set up a small (18") coldwater aquarium, no fish yet. Ive tried
to do everything right, everything is clean, I've got a small pico
filter running. I filled the tank with water, added conditioner and the
water has gone cloudy, its been cloudy for 24 hours now. I don't want
to put fish in until its right.

What am I doing wrong? Or is this a common thing? Can anyone help?

Raccoon