My last Giant apple snail went missing for a few weeks until i found it stuck in between two rocks. i got it out and it stayed in the same spot and didnt more for another 2 weeks. when i got my refugium to medicate a clown loach(which didnt work out) i put my madtom catfish and the snail in there because the powerhead add a ton of O2 to the water. After 8 hours of putting the snail in the refugium with the super oxygenated water, he out an eating. Added O2 will do wonders for the snail. only time i see them use their syphon is when the O2 levels are low.