Elodea turning light then dying. Help!

[Nabbig2]

http://imgur.com/FJFVyez

I got some elodea because it's supposed to be hardy and grow fast. I keep it at room temp (usually 60s sometimes warmer) and some of the plants have been turning light, and gradually rotting and dying. I have some in my betta containers-it seems like they do OK unless they are covered by a dark top (not getting enough light?)

BUT the picture I posted is a 10 gallon out in the open, it should be getting plenty of light, now the elodea is dying. There's no fish or anything else right now. What am I doing wrong?

 

[Fishman Dave]

Your elodea actually looks like egeria densa, a different plant that does better at slightly warmer temperatures which might also hint why it’s “melting”.
looks like a temperature issue so far with nothing more to go on.
What temps did it come from at vendor?
Is the temperature stable or fluctuate widely/ quickly/often?

 

[Nabbig2]

Your elodea actually looks like egeria densa, a different plant that does better at slightly warmer temperatures which might also hint why it’s “melting”.
looks like a temperature issue so far with nothing more to go on.
What temps did it come from at vendor?
Is the temperature stable or fluctuate widely/ quickly/often?

I don't know. But I have a small chunk that is in my betta bowl, at room temp, same temp as the others, and its very dark green and growing healthily. I don't know why that is thriving but the rest are dying