Hydroponic tomato fertilizer and flower pollination

[Icefisher]

Hello all,

My first attempt at growing tomato's hydroponically is going well! I am using a DWC system growing both a "fourth of July" and "Sugar sun" variety.

Can anyone tell me when in the vegetative growth stage is it time to switch to a higher potassium nutrient level?

Also, as the plants flower, when is the best time to attempt the work of pollination?

Thanks
Icefisher