Please help! Slow growth, curling leaves, tried everything

[Loco Roco]

Hey, guys, can you please help me with my problem?

I'm growing from the seed for the first time, I've always started with clones before. I successfully germinated, put them under CFL for a while, now they're under 600W MH lamp.

Setup
- 9 Bubba's Gift plants from Humboldt Seeds
- 110x110x160 growbox
- 600W MH lamp (Superplant)
- Coco

Fertilizers
- I put just a small amount of Jungle in da Box fertilizers + Supervit.
- pH 5.8

Now the problem:
Symptomps:
- Slow growth. I literally didn't see any change for a past weeek.
- Leaves curling as you can see on my photos
- Leaves drooping, look at it. Those plants look sad
- Branches are very close to each other but that may be a problem of the strain

Dates:
- Seeds germinated on 7.10.
- I put seedlings under 600W on 16.10.
^ this means the plants are almost month old. Are they supposed to be this small?

Probable causes / What I tried
- At first I thought the plants are freezing. The MH lamp doesn't produce much heat (it's in cooltube) and I use a humidifier that produces cool mist. Cool mist is the first thing I thought is the problem. I stopped using the humidifier for like a day or two, but it didn't help and humidity dropped to 30 % so I turned it back on. The temperature is 20.5 - 24 °C. Humidity around 50 %.
- Because of the cold problem, I closed a window a lil' bit. Not entirely, there's still a gap. But, I thought that maybe plants are not getting enough air. However, opening window didn't help and I used this technique before with much bigger plants with no problem.
- After reading some articles, I suspected my plants are suffering with bud rot. However, roots are not brown or slimy and there's no smell.
- I'm 90 % sure it's not overwattered or underwattered. I water them every day with little bit of water and fertilizers and next day, they're almost completely dry.

Thanks for any suggestions and help!

[Bud Lightyear]

You should be water/feeding daily with around 20% runoff and you should be measuring the feed strength..

Regards BL

[Bulls]

Hey buddy. They look a bit underwatered. As Bud said you need to feed them daily with 20% runoff.
If you really want to have success you better get yourself an EC pen. I would recommend BlueLab or Essentials.
Also your tent is kinda small for 9 plants. What size will be your final pots?
Is that all the nutrients you've got in your hands? Any Rhizo or Canna A&B?

[Loco Roco]

Thanks for the tips. I actually don't think I have any runoff so you may be right!
And I use Jungle in da Box ABC + Hesi Supervit (vitaminsú. I don't use rhizotonic, but I thought it's not neccessary.