I seem to be going through more juice with the Protank, but i have a theory about that. If you examine the Protank you'll notice the glass is much thicker than other clearos and most carto tanks (mine anyway). I don't think it holds as much liquid as it appears to. Adding to that, you may have figured out that the Protank performs better when it no less than 1/2 full, so you're filling it more often. If you're using a Protank you might not be using as much juice as you think you are.