Rockwell has started using a new gallon jug for acid and bicarb. It is taller than the old jug by about an inch, and has a much thinner handle on it. If you are using the Fresenius acid and bicarb wands as provided by the factory, they don't reach the bottom of the jug anymore and will leave about 3/4 of an inch of solution in them. You may have to increase the short hose on the wand that goes between the top and the hard plastic tube to get that last bit of fluid out. Also, the much smaller diameter handle on those jugs is very uncomfortable to hold for any length of time.