I just switched from Titan batteries with prefilled cartos to the OMG with tank, and let me say I AM IN LOVE. I have been trying to read as many different posts to see if I can answer my own questions but here goes; I am currently using a 3.5 tank with the OMG handle, and it has the DC 1.5 ohm in it. I saw a post that this may not be the best for this handle. Should I be using a SC 2.0 ohm? And Next question, do I wait for it handle to tell me to change the carto in the tank, or what? I was wondering if the indicator of ohms tells me its time.