You don't need the blue foam. Just make sure your polyfill is cut so it's not packed into the cart. Some of the carts come with way too much polyfill in them. All you need is enough for the fibers to hold the tension between the liquid. It works a lot better to cut it so with tweezers it slips in pretty easily....you aren't stuffing the entire space with polyfill. There's no chemicals in it to worry about washing out, it's cheap, and easy cleaned and replaceable.
Also, on the nicotine level...I smoked only 1/2 to 1 pack a day so I started with 6-11mg and found it too low. I tried the 24 and about blew my brain off. The 18 was a little too strong....hurt my throat, so I think the advertised levels are a little off. I think my level is around 14-16. At that level (I get it with mixing 11 and 18) I can put the thing down instead of constantly vaping. Sets your sites a little higher than you think you'd take then move down. I drip a drop of 11, a drop of 18...etc on my polyfill to achieve my goals.
Also, on the nicotine level...I smoked only 1/2 to 1 pack a day so I started with 6-11mg and found it too low. I tried the 24 and about blew my brain off. The 18 was a little too strong....hurt my throat, so I think the advertised levels are a little off. I think my level is around 14-16. At that level (I get it with mixing 11 and 18) I can put the thing down instead of constantly vaping. Sets your sites a little higher than you think you'd take then move down. I drip a drop of 11, a drop of 18...etc on my polyfill to achieve my goals.