If you are starting off your seedlings in this rubbermaid then no nutes. It is also not a matter of how much water but water level. Fill the water so that it is touching your grow medium until the roots grow and fall down into the water. Then you can lower the water levels.

How much water should you use then? Well fill it up and see how much your plant drinks between water changes and use that amount plus a little more so it never goes dry.