new hydroponic setup

[Victoria]

I am starting an 8 pot hydroponic setup which has 3 inch net pots in a 4 gallon reservoir (eBay) . It comes with a 4 tube fluorescent (2 red/2 blue) light, the pump and all accessories except seeds and nutrients. The set is made of black plastic. I am contemplating organic nutrients for better flavor but wondered if anyone here has used 50/50 with 1/2 being organic and the other 1/2 regular hydroponic nutrients.

Any tips on maintaining proper ph levels?? Is once a week enough to change nutrient solution?? This is new ground for me and I would REALLY appreciate any tips from actual hydroponic **vegetable** gardeners. For starters I will grow chard and romaine.