Hydro Nutrients

hey everyone! i have done one soil grow thinking about making my own hydro kinda like this one

http://www.youtube.com/watch?v=Ah3zrGRmx80&feature=youtu.be

but i dont really understand how the nutrients part works. how often do you drain and refill if ever? how often do you have to add nutrients to your water? is there other nutrients i need besides grow, bloom, ect.? any info would be helpful on this issue. thanks!

general rule of thumb is to change the res every 2 weeks. you also need to flush and add ferts every 2-3days. you need a good hydro fert for veg and bloom and you need a ph- acid like phosphoric or sulfuric acid. also need a ph and ppm tester to control the feeding

there are a ton of ways to feed your plants from easy measure and more to complex mixtures. I use advanced sensi grow/bloom with a few adv additives they offer mixed in. The main thing is to keep those ppm right! You can nuke your plants quick in hydro if you run them too high. Find a food and try it out just start with low ppm and work your way up. One thing I can say about using advanced is personally I have not used my PH meter in sometime now

im using earth juice and it says on the label to used with a complete hydroponic solution

What ratios of ferts are you using! I have a 50 litre bitch, just trying to fathom out best ratio as not to burn my 'more than splendid' white widow.