I might be able to offer another idea. First, I cut a circle out of plastic craft mesh that fit perfectly inside the intake tube of my python. My original plan was to silicone it in place, but if I had glued it inside the tube close to the bottom, the gravel cleaning action would have been impeded. I wanted the craft mesh about 8 inches up the tube, but I could not figure out how to get the glue so far up the tube. So I drilled about 6 tiny holes around the circumference of the tube, and used fishing line to tie the circle tightly in place.
The hard part was manipulating the fishing line inside the tube. I ended up using a thin pair of "kitchen tweezers", a strong light, and a lot of patience...but it works great now. No risk of sucking a fish into the line, and the mesh is open enough to let the gravel crud through. I think panty hose is too fine...some of the finer crud will be sucked thru, but larger stuff will collect. Not the end of the world though.
This mesh idea (and the pantyhose method) will NOT protect larger fish, however. A bigger fish is not likely to get sucked bodily into the tube, but it does not take much suction to yank the side of a larger fish up against the tube opening, and injure him/her. I have read in this forum about fish losing eyes that way, and had one of my own fish get an actual bruise. Some people say fish dont bruise...well, he had a heck of a mark on him for weeks, and he never did swim right after that.
Needless to say, I felt like a real schmuck, and have been far more careful ever since.
