ATO Float Valve and Adding Sand Question!


Well my 24 nanocube has been established and running well for a couple months now and my one little hammer is getting huge lol.. Anyways I want to set up an ato and im not sure what kind of float valve to get for the back chambers. I have the aqualifter and the 5 gallon jug and everything ready, all i need is the float valve. So what is a good float valve for a nano cube.

2nd question. My sandbed isnt very deep and I want to eventually add a jawfish. What is the trick to adding sand to a tank thats been running without creating a sand storm? Should the sand be dry or live?

Thank you all,