Elmer's glue, white glue, school glue and tacky glue are all different forms of PVA glue, which is short for Polyvinyl Acetate, in case you wanted to know the technical term. Any yeah if you don't need any kind of transpancy or water effects PVA glue isn't a terrible way to do this. I'd probably be more likely to go with a product like Envirotex lite tinted with a green wash for your basic stagnant murky sludge, then add woodland senics water effects if you want to create the illusion of motion.
I thought about doing a project like this once, but until I get unfettered access to a bandsaw I don't trust myself to make the cuts in the PVC both consistant and smooth. Though if you didn't glue the PVC joints this could make a really cool modular system...maybe someday when I have more time and more space to store my terrain.