2 plants in aerogarden led 70w

At this stage iv been researching and come to terms with overfeeding and reading horrible reviews of miracle grow and weed lol i cut the nute down to a quarter plants seemed ok to me typical amateur stuff i had no ph tester or ppm and the resoirvoir i didnt clean properly but started to notice drooping and dark colouring so researched and thought it was solved switched lights to 24hr due to cold weather in room and temp was droping 15-16c