I normally rinse them out then give them a swish about in a bowl of warm water and washing up liquid then another rinse. I then let them air dry before using them again. What you'll find is that some liquids stink and leave behind the smell than others. I'd also advise using similar liquids in the same tank, I have a tank for tobacco juices, one for menthol type juices etc.
Cheers me dears , got a few pods and tanks that need cleaning out, I think tanks might be a bit easier than pods, saying that, looking at the Zenith I think I will just plonk it in some warm soapy water. Thanks guys.