My alto reed sounds fine but despite rinsing after every use it got some black (fungus?) growing on it.
Soaked it in Hydrogen Peroxide until the bubbling stopped ( about 20 min), rinsed and used my thumbnail to scrape off the gunk under running water.
90% of it came off, doesn't look brand new but way better.
I'll try it later and see if it plays the same or better.