Get one of those green cans of Scrubbing Bubbles Foam. Put hot water in the resevour and squirt a bunch of scrubbing bubbles in there. Plug all the opennings up and shake it a bit. Do this a couple of times and it will be good as new. I've done this with quite a few dinjy looking bay resevoirs and they always turn out perfectly clear.

You gotta shake it, shake, shake it, shake it like a polaroid picshah!

....sorry....damned song was on the radio.