You will want more snails then that. You want to mix it up because they all eat different stuff. I have a 16 gal and have 6-8 small sand sifting snails, 3-4 nerite snails and about 6 cerith snails. I also have a few blue leg hermits and accidently got a zebra hermit, that guy is awesome. He doesn't bother the coral and he's all over the place. I also have a huge turbo who cleans great.