raise the roof?

So my plants have been acting strange lately. When the lights are on, they tend to "raise the roof" as seen in the pic, where the leaves get raised up really high. But when the lights are off, they get really saggy like they were underwatered. Actually they probably were underwatered those times, the soil was super dry, but I gave them a good amount of water a few hours ago and here they are, at it again. Other points to note: I added a Co2 bag a couple of days ago, temp stays high 70s to 81 tops, have a humidifier going and rh is around upper 30s, and they are in 1 gallon pots. I really don't want to see them looking all shriveled up again later, but is this high-fiving a cause for concern? Someone said Co2 was pointless since it all gets sucked out through the exhaust fan, however I have fans blowing from the bag onto them and Co2 tends to stay at the bottom of the tent, so there's a little exposure I guess, better than just regular air I would imagine. Oh, when I watered them good I did a ph test on the drained water and it was pretty acidic (5), so I ph-upped my nutrient water and threw that in there too. Hopefully that will take care of that issue. Any thoughts, advice? Haven't seen this before, just a little worried...

Looks normal.

yeah the leaves "reaching up" is a sign of good health
letting the soil go dry is not a bad thing as long as it's not too dry too long
happy growing

Mine always look so sad at lights off... Well in the middle of lights out. I just tell myself they are sleeping.

From what I know this is perfectly normal. Plants get tired I guess. Day time they drink in all the light they possibly can and then they get sleepy. lol . If that makes any sense.

Resources = IME

Everything's normal looking to me, they're taking in the light

mine do that but they point up allot more, it just happens every now and then, from my experience you have no cause for alarm

If the edges of the leafs start to "raise the roof", then that's a sign of heat stress.

Wow, so happy to hear this, and from such a large consensus as well! I guess I'll just keep an eye on the water then.