So my Nerite, Tod Jr., seems to be a very satisfied and happy snail, he roams around the tank and eats algae and such, he's very active even being about 1.5 years old. But lately every time he tries to sleep on the glass he falls down after about an hour. Usually he needs a little help from me to move him to something he can grab onto, but he starts moving around again afterwards. I don't think it's an issue with the parameters, which I keep at A 0ppm, Ni 0ppm, Na 0-5ppm. Is there anything I can do to help him? I want him to be able to rest without falling and it drives me crazy, please help.