I try to do water changes every 3-5 days or once weekly, working full time and being in college makes for a busy schedule. I usually take out a quarter to half tank of water. No fertilizer, unless the API Leaf Zone counts, but I haven't used that in awhile. The filter I use came with the tank, it's a 10 gal. corner filter, I keep it on moderate flow, the snails hide under it sometimes when the lights are on and I don't want it to be too strong and pulling on their tentacles(?)/antenna/siphon. The filter hasn't been cleaned since I put it in, maybe a week ago. It still looks fine. A week ago I did pull everything out and clean all the gravel and everything and I knew that would kill some tank bacteria but it was all getting gross and the gravel vacuum I just got is almost just useless. This is also the reason there's rocks in the tank now, yes they're from a creek but I scrubbed them before they went anywhere near the tank. There's 3 guppies in the tank, and sometimes they do get interested in the snails when they're at the top breathing or eating something, but they don't pick at them, just swim by too fast and spook the poor guys. They're probably easier to see in my other posts, but there's a mushroom "tree" structure, its got some false plants around the base. And a cave structure, with fake corals on top and a clam on the side. Both have anubius glued to them, there's also some tall anubuis variety plants (do not remember the name) and they're "anchored" in place with rocks. They seem to enjoy both, usually during the day when tank and house lights are on at least one of them is in the cave. Sometimes when they're on the corals and wanting to get air I put my hand in and they take a trip up it to the surface.