'excellent medium for' is correct and can be used in written English.
You can use this phrase to describe something that is a good method or means of communication, transmission, or delivery. For example, "Email is an excellent medium for sending important documents quickly and securely."
Twitter is becoming an excellent medium for communication among scientists.
Poultry provides an excellent medium for the growth of microorganisms.
Plaster of paris does not generally shrink or crack when dry, making it an excellent medium for casting molds.
"The auction room, as anyone knows, is an excellent medium for sustaining fictional price levels, because the public imagines that auction prices are necessarily real prices".
When mixed well with any of the commercial potting mixes, compost boosts growth and provides an excellent medium for the plants.
The response to recent columns, in which I suggested that social media and news aggregation have their downsides, taught me that, whatever limitations Twitter may have as a vehicle for discussion, it is an excellent medium for name-calling).
According to Paul Cernat, his influential circle was "an excellent medium of transmission for the modern spirit, an informal institution and one of the first coagulant factors for [Romania's] first post-symbolist modernism".
Once the soils are drained, limed and fertilized an excellent medium is created for the rapid spread of new soil fauna and flora.
These features make SCW an excellent reaction medium for gasification, oxidation, and synthesis.
Milk is an excellent growth medium for numerous bacteria, and the bacteria can increase rapidly in numbers unless the milk is properly processed.
Our findings suggest all-inorganic perovskite QDs can be used as excellent gain medium for high-performance frequency-upconversion lasers and provide reference to engineer such QDs toward practical optoelectronic applications.
