I dedicate an entire thread to what will be known as "The Sloshers".
They are the CPS 1000, 1200, 2000, 2500, and 2700.
So what the heck is a "Slosher", you ask? Well, here's a thousand words on it.
I define a Slosher as any blaster where the reservoir has an intake hole on a vertical (or steep) ridge/wall, designed to allow the water to easily splash and slosh upwards into the other section of the reservoir when capacity runs low. (To about 1/5 of the whole tank or so.) The result is that you have to be careful while pumping, and air can often get caught in; not good for a CPS.
Please do not mind the potato MS Paint drawings.
Anyway, this is not something documented or mentioned much, so I figured it could be worth its own thread. My preferred solution to sloshing is to add an intake tube to the reservoir so that the intake area is easier to pool up water.