This is very useful http://easyponic.com/nutritive-solutions/

I like canna nutrients,there the cleanest and most soluble you can get..good info here http://growww.weebly.com/hydroponics.html

I use this:

https://hydro-gardens.com/product/tomato-formula-5lbs-box-4-18-38x5/

Results with tomatoes has been great. Biggest problem I have is the plants grow so fast I have to keep up on the pruning. Be sure to check out Kratky's paper on using a float valve and external tank. This has been working great for me for tomatoes and lettuce, you can set up a large reservoir that feeds many smaller buckets/plants. I only have to mix up nutrients for the tank every month or so and with lights on timers they just grow themselves without any help.