So I did a res change on monday evening right before it was lights off time. I dont have a ride nor a store close enough for me to lug 10 gallons of water back to my spot, and the res had to be changed that day it was so low. Well i was in a rush to beat lights out, and literally as the timer clicked off, the res was ph' and everything was bueno...... except i forgot to plug the pump back in. So i had an epiphany 10 hrs later in the middle of the night and i took off running, plugged it in, and went back to sleep. Woke up during lights on and everything looked fine. Fast forward a cpl days and i can not keep my from dropping pretty drastically. Set it at 5.8 last night and woke up to 5.1... but as im typing this i stuck the pen in again just to see and its 5.5 .... should i just let it be and adjust it as i have been since the plants look healthy? Before this i always had to ph down, never even opened my ph up. Only thing that had changed is i switched to 12/12 9 days ago, switched from a t5 to a 400 hps and then replaced the hps bulb to a new hortilux bulb yesterday.