In your 'random length pieces of tubing', do you happen to have any eheim 12/16mm tubing?
EDIT: I just did some reading thinking the dwarf puffers were brackish water but there are several sources that say they are 100% freshwater. If that's the case, I'm totally tempted to buy them from you. God my parents are going to kill me for buying another tank to set them up in. 10 gallon enough for them both? Current water is 8.4 pH, is that too high? And what food have you been feeding them? -_- *compulsive buying*