jm1212 has the right idea .. your tank is too small for loaches. You can remove the snails in large groups by tempting them with food. After the lights go off for the night and the tank is dark, place a saucer on the gravel at the bottom of the tank, place a piece of sinking fish food on the saucer and leave for about 25 minutes. When you come back there will probably be several snails on the saucer and they can be easily removed with the saucer and food. you can similarly use lettuce, spinach, scallions or other fresh vegetables to do this, .. weight them down with a small rock. repeat til the snails are gone.