My two nerites have been doing a pretty good job of eating the algae and diatoms in my tank so far, but in the big picture, they still haven't really made much of a dent yet! It's been really fun seeing their little bite mark trails all over though, and that tells me they are working away at it. I ended up scrubbing the algae off the front glass for a better view of my fish. Then a week later I scrubbed the algae off the bottom too, since I noticed the snails never really went on the bottom of the tank anyways. My ryukin Clover sometimes rests on the bottom when he's sleeping at night and since I wasn't scrubbing it clean regularly, he started getting little red spots on his belly. It was nothing major, and it has already cleared up thankfully! So from now on I'll be cleaning off the bottom and front glass panes and leaving the rest for the nerite snails.
I noticed that the zebra nerite in particular had spent a few days cleaning off the overflow box and then one of the filter outflow pipes. But the second outflow pipe hadn't been discovered by the snails yet, so it was just covered in thick diatoms. It was driving me crazy! So finally today I picked up the zebra snail and placed him on the diatom-covered outflow pipe. He got to work cleaning it right away, and within a few minutes he had already cleared off one corner of it! These snails sure can eat a lot!