wow Pauly thats a tough one . 21 days in flower or 21 days in pots ,I will say 21 in flower .ok so 1.2 liters every other day, do you test to make sure they dried out enough. I use a water meter my fingers lie lol. when my girls get big enough I try to water every 3 day after giving them about a gallon of water sometime it takes 4 days for them to drink it all. as far as nutes go it should say how much to use on the label but I try not to give full strenth. I use 6 gallon buckets to water with and mix my nutes for 4 gallons of water and I've had some strains get nute burned at that level so I would start weaker. Pictures and a little more detail would help we are hear to help but you need to give us the tools to use lol