I found a pump that's about $5. I just want it to give some chaeto a little bit of extra swirl. Is there any reason I shouldn't use it? If it fails, it's fine. It's only chaeto tumbling. If it bleeds current into the tank, that's a bigger problem, but one I can prevent/find with a multimeter. Here it is:
https://www.ebay.com/itm/90-1450-GP...d52e88da7:m:mxiqo7G4Qt0UUKibdpAyXuA:rk:2:pf:0
https://www.ebay.com/itm/90-1450-GP...d52e88da7:m:mxiqo7G4Qt0UUKibdpAyXuA:rk:2:pf:0