Anti siphon value leaking

I have a 1" Anti siphon value that I just installed and it's leaking at the threads when the value is shut off. About 1 drop every 10 seconds..
1. When I put on the 1" adaptor, I did place one layer of teflon tape. Is one layer okay?
2. I made it hand tight and then used a wrench to screw it in a few turns. Is that bad?
3. When turning with the wrench, I didn't continue all the way and probably could have made a few more turns with some effort. Should I have tried to screw on tighter?
4. Is there a way to fix the leak without cutting off the value again and start from scratch?
TIA
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.. it's leaking

I use about 4-5 wraps

Nope, but its leaking so it isn't 'good' either

I suppose, you have to watch that you dont crack the valve if its plastic.

Nope. Nextime, you should use a union so you dont have to 'cut' it apart.
All the above said.. I did exactly the same thing when I put in my drip system manifold last year. Ended up with the slow drip. Took it apart (I left enough 3/4" PVC between joints so I could cut and use a coupling if needed) and tightened it up..drip stopped. BTW, I drained the system before winter but the spring loaded anti-siphon valve kept held about 2" of water between the valve and the pressure reducer. Over last Winter, that water froze and cracked the plastic RainBird pressure reducer. When I charged the system a few weeks back, there was a drip again. Removed the PR from the system (glad I put in a union) and it works fine now.
R
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5 to 7 wraps of Teflon clockwise, then rector seal pipe dope. As mentioned a union would of been nice
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