That's funny either way (not your monetary loss, just the situation) it was like when I bought a bunch of small amano shrimp, and they decided it would be an easier life if they just lived in the filter.
To answer this as best I can, they are slow growing, they suck up particulates like a filter, and they're extremely easy to care for: just give them a roll every so often so they doesn't brown on the underside where they can't get light.
The only thing you need to worry about would be Excel Overdosing, as these really aren't Moss Balls so to speak, there layers and layers of several years worth of algael accumilance. With that said, I couldn't kill them when I was testing this concern in my 29 gallon.
If you have one, you'll know what I'm talking about. I've got 5 in my 10g shrimp tank (Shrimp love eating off them), and I torn up one into three pieces for my small betta tank.