greenchilli - You have my sympathies. DH has always smoked a bit; I never. He went through a phase of buying a big stash and just smoking his way through it. Drove me bloody nuts. Him falling asleep on the sofa every night, never having the motivation to do ANYTHING, late for work all the time, etc. He also said it was for stress and put me between a rock and hard place like I had to say that he could either drink a lot, or have a few smokes.
Anyway, I'm afraid that I think you'll have to tell him how you feel. It eventually hit my DH when I said that when he smokes regularly, I feel like a single parent. He's "there" physically in the house, but pretty much unavailable to me as a person. I can't talk to him about anything important, and I'm not on the same wavelength as him. (Had a similar convo recently on here about cocaine use and not being on a level with him, but that's another story.) People do change when they have kids or at least their priorities should change.
You're not asking him to change his personality (something DH once tried to tell me), you're asking him to put you and your DD before his weed smoking.
Eventually DH and I came to an agreement that I wasn't asking him to never smoke again, I was asking him to not buy large amounts (as he frankly just smoked his way through it until it was gone), I was NEVER to find tobacco or papers or those teeny bits of weed around the house and that smoking was for occasional use at parties etc. Eventually I was able to make him see how being "tired" the day after smoking (you know the feeling) was affecting his work as he had no motivation. Sometimes he now goes out with certain mates and brings a bit home, which gets on my nerves, but it's really only a few spliffs worth - not the ounce he used to buy!
There's no simple answer and it does take a long time of bargaining, reasoning and reminding him how you feel.
It worked for me to keep playing on how alone I felt in the relationship when he was in his own world. Perhaps there's a particularly feeling that really gets to you that you can talk about?
Most importantly, I had to try not to nag, and never talk about it when he was actually stoned as it gets you nowhere as you know.
It does put one at a disadvantage when you do or used to do drugs as well. It's so easy for them to say, "But you're the one who has changed," or "it never used to bother you."
Persevere, because I'm sure you feel he'll be his "old self" when he cuts out, or drastically cuts down the weed.
I don't know if it's an option for you, but recently my DH decided (after some encouragement) to have some Cognitive Behaviour Therapy. It's helping him to learn to deal with the stress of his job, and his inherent lack of motivation and other personality disfunctiionalities and making him feel less like he needs a drink/ smoke after work to relax.
I wish you luck.