For your torpedo gas use a can of PROPEL . This is used for air brushes etc. It comes in a can and you can use the filling hose kit that you would have used with the freon cans. This stuff is sold almost everywhere like in hobby and craft stores . You cannot use compressed air to propell your torpedoes because the air would escape almost at once . You need a liquid gas such as PROPEL , when you fill your storeage tank you have the can of PROPEL UPSIDE DOWN so you get the liquid portion , if you fill the tank with the can upright you will only get the gas and once again your torpedoes will go nowhere. When the torpedo is filled and then fired the liquid PROPEL will stay in the torpedo body longer as the liquid keeps on expanding and your tin fish should travel a good 30 to 40 feet . The key here is to use a liquid gas just a compressed gas like air . I have been using gas tin fish for 5 years now , if you need any help feel free to email me .