lol. Be careful what you ask for because you may just get it. Crash course vaping ohm's law:
Volts = push/oomph.
Amps = # electrons flowing past a point per second..... not the pressure, but the #
ohms = resistance. Flow restriction. Also sort of the "draw allowed".
watts = heat/power (volts * amps)
ohm's law calculator:
Ohm's Law Calculator
Use the calculator and plug in 5 volts, and 2.5 resistance then press calculate. If you know any 2 variables, you know em all.
So, You have a 5 v PT and a 2.5 ohm carto. Watts (heat) = 10 watts. A bit high, even at 2.5 ohms. Your power supply must be supplying the necessary amps. Some may say "I use 2.5 ohms at 5 volts and it's fine", but you can assume that their power supply is insufficient and doesn't really supply the full 2.0 amps so voltage suffers and they end up at lower watts.
Another handy formula is V * V /R where V is voltage (squared in the equation) and R is resistance (ohms). This gives watts. 25/2.5 = 10
Vaping around 6-8 watts is good. Too high = melted plastic. Get ya some of them thar 3.0 ohm atties for a good vape. Since 25/3 = 8.3333.
Now that you know V*V/R you can calculate any device/atty combo.
See the modder's section for a lot of info. You may also research/Google "basic electronics".
FYI - Some juices "burn" faster than others. Higher voltages heat faster. I get a burnt taste (not plastic tho) from citrus flavors quite easily.
Have fun!