JBJ 24G & 28G Nano Cube Replacement Pump JBJ 24G & 28G Nano Cube pump is the replacement pump for all 24 & 28 Gallon JBJ Nano Cubes. This pump is marked either Model SP1-1000E or SP1/1000 JBJ has used both pumps with these tanks and they do not differentiate between the two pumps Sometimes they send us the SP1-1000E and sometimes the SP1/1000 (both are pictured).