If you don't have a long brush and the hose is longer than that bent clothes hanger you managed to unwind with a pliers, you can still "mouse" it out. This works with a hose of any length.
Make a little ball of cloth that fits easily in the hose, and tie it up with string. (The soft mouse.)
Leave a "tail" of string on the mouse much longer than the hose. (Hold that tail!)
Suck the cloth through the hose. (Not by mouth! Yuck!)
Use a vacuum cleaner, and just seal the hoses together temporarily with duct tape. (Hang on to the string tight so you don't loose it all in the vacuum cleaner. You can always tie a pencil to the free end.)
Once you have a long string through the hose, tie a bit of scotchbrite in the middle (The rough mouse) and run it back and forth by drawing with the string. Minimum string length is twice the hose length plus some grippage for you and the mouse.
This will knock out tough algae and snail egg goop. (I don't know the real word for snail goop, but it sticks like glue.)
This works for old pipes too, and you can definitely make the snow globe effect after.