How much nutrients do I need for 3 plants in an NFT system with 250w light

Im gonna start to grow 3 or 4 plants and I need to know how many litres of grow and bloom nutrients I will need during the 10 weeks. and how should I mix it with the water? Cheers

First of all you'll need to make 2 posts about this in the same forum, preferably one right after another.

After that it really depends on how big you're going to grow your girls out, as well as how big your reservoir is, if you plan on using 50% solution or what.

I prefer to premix my nutes/water in a separate reservoir then pump it in once I get it right where I want it.

Look into a 3 part nutrient kit consisting of "Flora-grow" "Flora-micro" and Flora-bloom", I've had excellent results with this line of nutrients. Be sure to carefully read the instructions! (crucial)
With a garden that small your reservoir will be less than 5 gallons which allows you to just dump it every 2 weeks and give your ladies a fresh mixture.
Your plants will always have exactly what they need without calibration!