Ideally you want you want to keep the RH pretty high during veg 80 is good 75 is fine if you have the right temp 45 is to low...I recommend downloading a VPD app, I used tent buddy it also has PPFD checker as well... at 77F you should have a Rh of 77 to give you a VPD value of .89 in veg they should run between .80 and .95 and in flower .96 and 1.15 VPD, you might have to get a humidifier...I have a inkbird temp control and a RH control as well which my fan and humidifier were hooked to and now I have my dehumidifier hooked up to bring the RH to 50 ish and I try to keep the temp at 68F and 51 Rh for a VPD of 1.15...Keeping things in the parameters are difficult without controls and thr inkbirds are a cheaper better solution...