I haven’t ever seen a MTS attack a pond snail. I have many tanks with both of them. What I have observed is that pond snails seem to prefer plants and all of the tanks with both types do have plants. MTS are more carnivore than the pond snails, so if the primary source of food is Fish Flake they may out-compete the pond snails. Pond snails also eat more algae and in a super clean aquarium this would also allow them to be overtaken by the MTS population. Could this be what happened in your aquarium, or did you actually see the attack? Are you sure you don’t have assassin snails? Mystery snails will eat flake refuse as well so they provide more competition to the MTS than the pond snails. I do observe the pond snails doing very well in with the mystery snails. Sorry I don’t have a definite answer for you but they seem to coexist very well from what I’ve seen.
Sorry to hear they haven’t been as prolific as you’d like. You could be right, It may be your water conditions. Do you have any live plants in with them? What temperature are you maintaining? Have you tried cycling the water temperature? How much light is your tank receiving and have you tried varying the day length? What other fish are inhabiting the tank? I recommend you try to get you aquarium environment as similar as possible to the conditions these are born, bred and raised in as they are extremely prolific in the conditions / parameters around here. They are kept alone. All of my fish have been raised in Florida Aquifer fed well water which has a pH of 7.6 and conductivity of 290. They are born bred and raised in 55 gallon heavily planted aquariums all have substrate. I feed them a large variety of food. I feed them fish pearls larval diet, occasional freeze dried and frozen bloodworms, algae, live scuds, live and freeze dried daphnia, live ghost shrimp larvae, freeze dried Cyclops, mosquito larvae and fresh hatched brine shrimp. Most of these dry foods are available from www.kensfish.com. The live foods are cultured among the fish within the aquariums. I do not want to make this seem overcomplicated though, they are easy to care for. They are fed this large variety of feeds and are exposed to natural sunlight to bring out their best coloration and to maintain long term health.
They will thrive on just Tetramin or Ocean Nutrition flake food in a heavily planted aquarium with a ph above 7. The temperature in the greenhouse where they have been raised varies seasonally as they are in aquariums within the greenhouse. During the winter the water temperature will average 72 (64 in morning / 84 late afternoon) and during the summer 82 (72 in morning / 88 late afternoon). The variance is a natural occurrence these fish are well adapted to since they were originally collected from small ponds in hot climates.
They grow faster and breed more often in the warmer temperatures. They tend to drop fry the day before a full moon as well as the first day of the waxing moon. You may want to try using moonlight to try and trigger them to drop. Another trigger is to not change the water for 10-days prior to the optimal lunar cycle days and then perform a water change on either of those days. Hope this helps.