Final 2 weeks, how to flush properly?

Preliminary information- First Hydro Grow, 1 light and 1 4x4 ebb and flow table, 1 35 gal Res. Currently they are on a two time daily 15 min watering schedule.

So I'm about to approach the 2 week mark prior to harvesting 3 of my 9 ladies. Here in lies the rub. I have 9 girls but they are in different stages, I started a set of 3 each one week apart.

So how do I properly flush the 3 oldest and still maintain proper nuets for the other younger ones.

Here is what I am thinking: I'm going to take out the 3 oldest from the ebb and flow table and just put them in a tote with fresh water in it, so they will just sit in the fresh water and I will replace as needed.

Is that too much water for them just to sit in the water?

Any other suggestions would be highly appreciated.

i would pull them like you say and get like a bath tub/pool or something let the roots hang in there but you will def need a bubbler because these roots will need oxygen.