My euros do better, growth-wise, when I separate/divide them. If I leave them in a bin, crowded, they do not grow to bait size. My only other thought is to make sure the worms in that bin are just euros.

are euro's different than red wigglers? far as i know only red wigglers should be used for vermicomposting

Euros are European night crawlers. They are not 'composting worms' per se. At the same time their 'specifications' make them much more suited to bins than the north american night crawler.

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Euros are different than redworms. They grow much larger. They like wetter, cooler conditions. Like I mentioned before, they will not grow to bait size in a crowded bin. They most certainly can be used for composting and eat alot. You would get the best of both worlds. That being said their are more prolific worms that will do the same job, only faster, if you are in it for the compost only.