While researching Planaria I came across something called Detritis Worms which at least by the pictures appears to be what it is. It says they are not harmful but come from needing to clean the substrate. I have only been keeping shrimp about 2 months & do weekly water changes & nitrates remain below 10 but have never vacuumed the substrate yet. My son is definitely guilty of overfeeding though, I don't think he realizes how small these shrimp are. This leads me to another question HOW DO U VACUUM THE GRAVEL WITHOUT SUCKING UP THE SHRIMP? No problems with the fish tanks, do it with every water change but have yet to try it in the shrimp tank yet. Plus this tank so small it hard to get the python in there. Thanks
Fluval makes a smallish vacuum wand which is thinner to get in between. Made for the EDGE. I have a similar issue with a very planted 6.6 Edge that I had the Planaria problem with. Right now what I am trying is to vacuum into the sand in the bare spots and then move over the rocks and vacuum there. Then next time vacuum better in the bare spots and move the rocks back where I prefer them, trying to avoid the roots.
Also I have used a chop stick and swirled it around in the sand to stir up the particles. This gets the shrimp very excited at the chance to nibble on new crud!
As for sucking up shrimp, I bump the plants I will be cleaning with my finger on the suction tube end to stop suction, then start the vacuuming. Mostly the shrimp vacate the area but I have sucked up a few mostly when they were babies. I use a white bucket so I can watch the bottom sediment. using the chopstick after the water is still, wave it next to the sediment in a slow circular motion. Adult and baby shrimp swim in a jerky darting manner and it is easy to see if you got one. Just net it and put it back in the tank.
Of course this isn't with a Python, it is manually..., you could fill it back up with a python though. Just for cleaning the substrate. Still do normal water changes as usual.
Show your son maybe even with a magnifying glass, how small their mouths are, then just ask him to think about how small their stomachs are and how much food he thinks they should get and put it on to a piece of paper drawing how tiny the mouths and stomachs are. Then put the amount of food he should feed on the paper to get an idea of how much it should really be...Depends on modifications based on your sons age... You can give him a little measuring spoon for the correct amount of food per feeding.
I am an over feeder, even after I cut them back half! lol It really does make a difference on water quality/ required pwc frequency. I am a recovering over feeder. hahaha