Actually this is a very common question not exactly common knowledge as it can vary greatly from grower to grower, and can be completely elusive to those new at hydro depending on the system used, but the best advice I can give you is start off by just giving them a basic diet. breakfast at lights on, lunch in the mid day and dinner an hour or so before lights out, each beaing 15 minutes each this is the way I run all my ebb n flow setups and I have a few different versions (Bit of a hydro horder like to change it up almost every grow) after that just watch the progress each day if they seem like they are asking for more you can either extend your lunch to 30 min or add another 15 in there somewhere any more and your probably over doing it!!! the next best piece of advice I can offer you is study study study buy books read all the hydro threads here ask the rite questions to the rite people and befriend them so you can get an educated experienced answer when you need a real question answered! Hydroponics can be very difficult for some, proper knowledge on how it works (far different from soil) is the best defense against failure!!! You should start a thread/journal of this grow (be sure to add pictures) and ask questions make lots of updates. This will save you a ton of hassle on your next grow since you can just go back look at what went wrong or rite and avoid making the same mistake twice hope this was helpful for you feel free to ask me anything else u may need help with and I will do my best happy farming and Jah bless

Thanks so much for your reply, this is a really old post no one was brave enough to answer. I understand now why I didn't get any answers. I've gotten thru veg and now I'm 1 day into flower and I understand it's fine tuning that's individual to each hydro set up and basically my questions can't be answered.
I measured my fertilizer wrong and burnt them a little (I was off on the size of the res) And I'm sure I'll make a lot more mistakes before I get it figured out But it's nice to know I can now Ask another hydro grower. Thanks again

Ah phooy all your questions are answerable with enough detail on your part you just have to take everything with a grain of salt and apply it to your specific technique and knowledge of your current grow and I did realize this was a few weeks old but wanted to try and get you on the rite track even tho every one has a difference in hydro there is one rite and wrong way to do it hydroponics is a scientifically controlled environment and method of growing as long as you follow the rules (making small adjustments to fine tune it as u said) everything is laid out in black and white you just gotta do the proper studys and research and make note of every thing you, your system and your grow room does or goes through. Here are a few books that will help you greatly (these are not your average grow books)

You may need to grab this to understand that I know I did

And these are good ones to have as well
Hope the best in your endeavors and happy farmin