I've had success with the tank replacement cartos. I use ~75VG/3PGA/22PG. It's not VERY thick with the high PGA. I found that it's neccessary to pull hard on the carto, sometimes, to get the bubbles to exit into the tank for wicking. I've literally pulled a dozen times without firing until bubbles stop escaping. Generally, I haven't had to perform this ritual much, tho. It's worth a try.