You can also go to weedfarmer.com it helped me alot & fox farms comes stock with all the nutes you need for at least 30+ days like I said what I did fixed mine with the same problem
The R/O system would completely clean the water & having a ph closer to 7.0 will insure a neutral amount of N.P.K. that your plant will receive.sorry if I am wrong
I am going for 6" to 10" container I use fox farms ocean forest and it says I don't need any for about 30 days my plants are going from dark green to lite at 18 days I am just afraid of over fert thanks for any help