yeah, nothing special needs to be done. just a simple resetting of your timer and as far as ferts, use them at their normal time when you switch. you might even see a need for more N after a month or so of flowering and it does no harm giving them a dose of veg ferts, in case the plants start lightening up or show other signs of nitrogen deficiency...i do it with nearly every grow and is always needed for the longer flowering sat's in an outdoor environment. you need to be more careful in an indoor grow as ferts will build up in soil, but you shouldn't have that prob in your hydro grow and only added it for the dirt farmers reading this.