it is. I've had it in almost all of my tanks at one point or another. Me personally, I used red slime remover to be rid of it. Put it in at night and gone by the next morning.
My corals and fish did not have any adverse reactions to it and it you follow the instructions it works really well.
You can also vacuum it out the best you can, up your water change schedule and reduce nutrients going in and that will eventually work as well. Good solution if you don't want to use chemicals.
As far as ro
waste water, i have mine going to my flower bed out back, perfectly fine for that. You could even run it to your washing machine if you wanted. lol