I usually water them when needed like every 3 days @ roughly 1/8-1/10 of what the pot size is , for example if u got 7gals like me Right now every 3 days I be giving em 1 gallon between every two of the bigger ones (1.5-2 liters ish) but u gotta build em up especially in a big pot and small seedling like I did this run. And what u mean as nutrients change exactly? Cuz I been giving mine advanced nutrients micro grow and bloom with voodoo juice I just cut em off that for now tho u only use it first two weeks then first two of bloom eh.. the most I’ve given my plants so far for doses was 1.5ml micro 1.75ml grow and 1.25ml of bloom in a 4 liter jug , I did a double feeding back to back like that, like I fed and waited for to dry out and mixed up I think 1ml of each on the 2nd run, and now I been slow flushing the nutes through the medium for the last week the last couple feedings been straight PHed distilled water