snap, crackles and pops, those are all normal carto sounds. this happens when the juice hits the coil/wick. enjoy. cartomizers, ce4 stainless can be used in a tank. you have to prefill your carto using the condom method is common, you can also drip your juice in, average of 20-30 drops, just add a few at a time and let it absorb. You can also use a syringe.
what I do , is use a syringe and I add the drop thru the holes that I punch a few drops at a time if it is taking a while to absorb I put it to my mouth and sort of inhale so I gets sucked in. I find that it fills up faster and the juice gets down in the carto more efficiently. I fill a syringe with about 1 ml of juice and start filling thru holes and then I top off thru the top till it looks soggy on top. Pop it in my tank take a short dry hit to see a few bubbles and go.