Clown eggs are ready to hatch, water ?

My Picasso clowns have been laying consistently over the last 6 months and are now producing steady good size clutches of eggs. I have rotifers on hand as wel as green water, nannochloropsis for the rotifers as well as roti-food. My question is I have a 2.5 gal tank for the hatch. Should I use water out of the existing tank where the eggs are or should I mix new water? Also souls I keep nannochloropsis seperate or is it ok to add some to the larval tank ?