Low Humidity Seedlings

I have a bubbleponics sysytem, I germed my 6 auto MI5 by placing them in the rockwool (after soaking 24 hours). I thought I had some time but the next morning they begin to poke out and by yesterday they were on life support.

My couple days old seedlings were looking really sad, very droopy, funky color, and I knew I had to act quick or my babies were doomed. I searched and figured the problem to be low humidity (18% with 83 degrees). I tried towels, humidifiers, nothing worked. The highest I could get it was 23%.

I looked around and saw a pack of clear plastic cups and it dawned on me. I put one cup over each net pot to create a humidity dome. Just checked on them and they look better, not out the clear but hopefully chances improved. How long should I keep the cups on them? I have the 400w MH high up, my tent is 3x1.5x5 so it's at least 4 feet from the dome.

Maybe this can help someone else, idk, I'm baked and felt the need to share.

yikes maybe you should get a humidifier

experiment with the dome i take mine off atleast 6 hours a day and once i have good roots i leave it off, a 20 dollar humifier would work wonders in a tent that small, if you tried one and it did not raise the hum, then i dont know what to say get a bigger one spray water in the air inside teh tent, whats other people say about teh humin the area your sensor could be wrong.

I had a similar problem, $25 humidifier from walmart did the trick.
Also having a meter to measure temp/humidity helps a lot.

I tried a humidifier. Problem is, I have to keep the tent door open just to keep temps under control while i'm waiting for my fan. My central a/c is on 60 and i think that is causing the dry air. The humidifier was a friend's who had it laying around the house so it may be faulty but I don't want to spend money on one since I'll be getting my fan tomorrow and will be able to close the door and turn up the a/c.

The domes are really helping, I checked this morning, the seedlings are not as droopy but the stems are purple. I hope I didn't shock them with the humidity domes. They were in low humidity for two days before I realized the problem. I know it can be genetics as well, MI5 is known to be purple, so I won't freak just yet.

I'm thinking of removing the domes when the roots come through the net pot or is that too late?