You should also keep check the coolant level in the radiator as well, especially with a leak. Typically, the system relies on the draw of vacuum to pull coolant back in from the tank. If the system isn't sealed, coolant leaks out, then air gets sucked in before coolant does from the tank, and you have nasty problem (sounds like you already do anyway). As was said, replace the problem part, get it filled back up. Also keep in mind, if one hose requires replacement, ask yourself how many others do too. They probably all could benefit, as the cooling system is only as strong as the weakest part.