My daughters one 3yrs the other 7 months are producing a lot of eye rheum even during the day,what could it be and what can i use to clean their eyes?

Eye rheum?: Haven't heard of "eye rheum." If we are talking about conjunctivitis, "pink eye" usually means a viral infection, sometimes a bacterial infection, sometimes allergies, or occasionally other problems. Symptoms resolve in a few days or up to a week or so. A pediatrician usually checks a child if symptoms are worse than mild, and refers to an eye doctor if symptoms are persistent or worrisome.