I've actually tried a number of different things:
- 510 with polyfill (fine for the first fill or two but downhill from there)
- 510 with PTB (didn't wick well for me, tried a number of variants with this, including folded, rolled, plug+straw, nothing worked well)
- 510 with nylon scouring pad (worked better than standard filler but only for so long)
- 510 with Fluval (best one I tried so far, and the one I use if I'm using a 510 cart)
- 510 Mega with regular poly (works about as well as a normal 510)
- 510 Mega with Fluval (didn't wick well at all; that much length without any extra girth seemed to trap the liquid in a partial vacuum)
- eGo XL with Fluval (leaky mess; Fluval couldn't trap and hold that much liquid no matter how I compressed it)
- eGo XL with polyfill (surprisingly working quite well so far, but it hasn't been a full day yet so time will tell)
Going to try the blue foam tonight when I can get to the pet store to pick some up.