This is strictly an observation, I use 3 Crowns all with the 0.5 coils. I've tried them in temp (316L) and they just don't work for me. With that said I get my best vape with this tank and coil set-up in power mode (temp off in my profile) at 44-45W depending on the juice I'm vaping. Most of the coils will initially read 0.53, but after I release the fire button they will read 0.63-0.65. If I just tap the fire button once the ohms will read 0.53 again. I may be way wrong, but I think this behavior has to do with the material the legs may be made of. Anyway, I would think 70W would be more suited for the 0.25 coil. Try your Crown around 45W in power mode and see what you think. With that tank I never worry about dry hits. I've gotten dizzy trying to get a dry hit Didn't mean for this to be so long, best of luck. Joe