Also, i'm not familiar with the 901 carts, but you should def ditch the poly fill and get some of that blue aquariam foam. You can get it at pretty much any pet store, or find it online. it is the "MarineLand Rite Size U". works like a charm. You just fill ur cart almost the entirt way, then cut a little square of the foam, and use the foam as a plug. That's what i have been using with my 510, and it works like a charm. Made my entire
vaping experience that much better!