I had these in my Red Eared Slider tank a few months back. Not sure whether your tank inhabitants might snack on them, but danios are great at eating them.
Paul
That Sucks when you get Planara always use a gravel cleaner to get at them from under the rocks and in them as well I have done water changes before and if you dont use the Gravel cleaner you wont do much, I have noticed that planara can affect an algae eater i've seen one of my plecos die when I noticed I had quite a bit PL