Trying fast buds for the first time

First time growing using RO. Started to have calmag issues middle of week 2. Luckily this one didn’t get brown spots on leaves but was looking sad. Once I added that they perked right up! Hoping I didn’t stunt the growth potential. Last grow I ended with a fungus gnat problem. I thought I got rid of them but appear to be back. I have a fly trap in tent the full grow but 2 days ago I started adding mosquito bits in the water and diatomaceous earth on top when dry. Seems to be helping.