sorry i'm not sure what thread blu is
The Blu cart is a 510....
After refilling a couple of my old ("original") Blu carts...I bought some new BLANK carts and filled them with my own juice....
The difference is ASTOUNDING!! It's like trying to compare a Porsche and.....a Yugo!!

Granted, new carts won't turn a Blu into an "all-day sucker".....but it VASTLY improves the experience!!
The trick is making sure none of the juice gets into the center tube when filling....try to use the smallest "nozzle" device you can...SLOWLY fill, dispensing juice along the INNER EDGE of the tank while SLOWLY rotating the cart....this will help more evenly disperse the juice to the "wicking" material...
I usually let the cart sit/stand for 1/2 hour or so....then repeat this process to assure the "wick" is saturated.....
HTH!
Happy (vaping) Trails!