What causes weak stems? (laterstageofveg)

[lazer420]

I have been growing several different strains now, for a few months. They were stunted early on due to lack of light (12's) I have since upgraded to a 1000w cooltube. This last week they shot up, but the stems of new growth are very weak. Not brittle, but soft and floppy. Also, have twisted leaves. what's up with that?? I do have some pic's that I can post if it will help, but I figure someone probably has some reasoning behind weak/soft stems.
Thanks everyone.
Lazer.

[killerweed420]

Have you got a good fan blowing on them?

[BobBong]

air movement inside the room is very important. strengthens stems and roots.

[Faddenator]

air movement inside the room is very important. strengthens stems and roots.

Absolutely. It's as important as gravity is for our muscles!

[cigarettes42]

twisted leaves could be a fluctuation of your ph. also vegging with a 1000 watter could make the plant vegetation out grow the root growth. if your vegging with that strong light make sure you give it some dark time rather 24/7. also good aeration in your root zone can achieve stronger roots making stronger stems.