I use General Hydroponics regular Flora series and have used Flora Nova. I have been very happy with the results.

I don't keep my germinated seeds in a bag. I put them right into my hydro system and turn on the lights. Though you are supposed to wait until they break the surface before turning on the lights.

Looking at my notes, I see here after about a month of growing three plants, i was adding 2 gallons of water to my 18 gallon reservoir just about every day. So i would suspect you'll be adding water like crazy to a 10 gallon reservoir growing twice as many plants. At that rate of water usage you should be changing the reservoir every week.