Re: How can we tell if Elodea are alive?

Fleshy leaves with a nice green color would be one indication that Elodea was 
alive. If Elodea was brown or dried out, it would probably be dead. You could 
also see if bubbles of oxygen gas were produced when it was in water and exposed 
to light. Make sure the gas bubbles are not just forming because the water 
temperature is increasing due to heat from the light. Gas solubility in water 
decreases as temperature increases. Another possible method is to examine an 
Elodea leaf under the microscope and look for cytoplasmic streaming.

Elodea growth will be affected by light level, temperature, mineral nutrients, 
carbon dioxide concentration in the water, diseases, pests, and water 
pollutants.