To add my voice to the confusion, every 510 round blank cartridge I've had has been almost double stuffed with polyfil which has made filling and topping off annoying. I started ripping the fillers in half lengthwise and had much better luck.
I switched to 901 whistletips for my 510 and that's been MUCH better all around. Initial fill is about 17-20 drops and the material they're stuffed with wicks like a dream and top offs are 10-15 drops without having to fiddle around with tweezers to knock out air bubbles.
I still don't know what the filler in the 901 carts is but it's not polyfill/fluval, it's more like poly-sponge (Whatever that may be). Depending on the liquid used they get a little gunked up after a couple days of heavy use so I just chuck them in a box. At less than $2 for ten I'm not worried. I've got a couple that are still performing like new after 3 weeks of heavy use and that seems to be because of the
juice.
. Anyone more familiar with what the substance is or if it should be of any concern?
