Well, bladder snails are like aquarium cockroaches, they seem to live through everything. It doesn't take much overfeeding or algae for them to explode in population which is why most people see them as pests (me included). They're not super proficient in clearing algae because they're so small but they will help manage it if you don't mind seeing them all over the glass. Some people actually like them. Also, they are one of the big reasons people go for tissue culture plants. It's hard not to get non-tc plants that don't have bladder snails or eggs on them. my very first tank had an explosion of them and it took about a year to finally get them widdled down in population to the point I hardly see them anymore. I've been very diligent on making sure they don't get into my other tanks.