I go by the ProTank chart for suggested volts. Using the the formula of Volts x Volts divided by Ohms = Watts will give you the sweet spot. For example I am running a 1.8 head and ProTank suggests 3.1 to 3.4 volts, so 3.2 x 3.2 dived by 1.8 ohms = 5.6888 watts (If you are using the 2.5 ohms head just apply the same formula for Ohms Law). Some juices I run at 5.0 watts, some at 5.5 watts, and some at 6.0-6.5 watts max. Running at any higher wattage gave me more vapor and heat (which I didn't need), but the burnt taste was not worth it. If you are using a VV only PV, I suggest using the appropriate voltage (see ProTanks chart) depending on what ohms head you are using. Your heads will last longer and the taste will come out more, unless you are after a hotter vape which BCC's aren't designed for. IMHO.