Hi folks , i just got my NFT system and i want to be sure about my concentration of nutrients, the label suggests 1 ltre of nutrient to 250 ltres of water, the tank i have looks like it only holds around 20 litres, i will confirm l8r once i fill it. i reckon for 20 litres of water i would need to add 100 ml of nutrient, i will only add 50ml to start with. can any of the pro,s confirm my calibration.