What kind of feeder, klm? And what's it made from?
For regular cleaning, I'll soak feeders for about 5 minutes in a weak solution of bleach (maybe a TBSP to a gallon of water), then rinse thoroughly. If it's a wood feeder, I'll soak it in fresh water for another 5 minutes as the 'rinse cycle'; if it's plastic/metal, I just make sure I've rinsed all the surfaces well under the tap. Some of my feeders can be dismantled, so I soak the individual pieces in the bleach solution, then rinse, dry and reassemble.
If the feeders were really groaty, I'll soak in the bleach solution, rinse, use a bottle brush or toothbrush to clean off the grunge, then soak in the bleach solution one more time before the final rinse.
"We are--each of us--dying; it's how we live in the meantime that makes the difference."
"It's not what you gather, but what you scatter that tells what kind of life you have lived!"
"Be kinder than necessary, for everyone you meet is fighting some kind of battle."