In need of serious HELP!

I am currently growing some Super Skunk and the lower branch's are turning yellow and die'n are no longer developing! This is gonna be A mother for my SOG system. The plant is around 2' off the top of the pot, It is in A 5 gallon black plastic pot with A 400w metal halide on it and 20" off the canopy. My nutriant choice was Ionic Grow formula (was sugested by my neigborhood grow shop) being added at 5ml per Ltr. I used Fox Farm ocean soil and am watering everyother day giving it A total of 2 Ltr's of water at A time..... According to everything I have been reading it sounds like A nut lockup so I have flushed with 10 gallons of plain water with A PH of 6.3. Someone was also telling me that my soil PH is off so I went up to the store and was gonna purchase A soil test kit with the capsules that you add to get your results and the same guy that had told me to use the Ionic told me not to worry about my soil, I think he has A clue on what I am growing but I can't just come right out and say what it is! I need some serious help and am getting kind of upset since I seem to be doing it wrong or something, come on it is A weed how hard is it to grow? If anybody can offer me some help it would be greatly appreciated.

I have also been looking to switch over my nut's to the Flora series if anybody has anything to say about those would help....

I would recommend you switch to Fox Farm organic nutrients.
It will take a while for your plant to come back so resist the urge to over water.
Your soil looks soaking wet so don't try anything else till your soil dries up and you should probably water with 4 liters at a time.

I had just finished flushing, so swithch to the flora and water 4 liters how many times a week? I do have A moisture meter, but how moist should I keep my soil? I was using RO and switched over to well... I thought that it was A calcium def. at first!

Sorry missread what u were saying I was watching tv, wich of the fox farm would u recomend? And at what dose?