Hi. It's best not to use a low resistance (less than 2.5 ohms) on a lavatube. The LT will work, but it will limit the voltage so you don't burn out the carto or atty. It has a 2.5amp cutoff. That means no matter what voltage you set it too, it will keep the voltage low enough that you don't exceed 2.5 amps. To get amps, you divide the voltage by the ohms. So, for example, if you use a 1.5ohm cartomizer and set it to 5 volts, it won't give you 5 volts because 5/1.5=3.33. It will only give you about 3.7V because 3.7 volts/1.5 ohms=2.47 amps, and you can't exceed 2.5 amps.
If you use a 3 ohm carto, you will be able to take advantage of the full range of voltages available on the Lavatube. You don't need any other resistances, either higher or lower. 6 volts/3 ohms = 2 amps, and that is well below the cutoff.
All that said, the new version 1.5 Lavatube is coming out and the 2.5 amp limit will be raised to about 3.2 amps. That will provide the ability to use lower resistance cartos and also will let you use higher voltages with dual coil cartos, which don't work well on the current lavatube because it detects them as 1.5ohms and lowers the voltage below the point where they work best.