MTS showing redish purple shells?

[SpicyFin]

Some of my MTS are showing reddish purple in their shells.... is their anyway to encourage this trait to express more?

[KoolFish97]

This is only going of my understanding of breeding and genetics. Snails may be different keep that in mind. 

I would seperate all the ones with the desired shells and place them in their own tank. Keep them super well fed and breeding and the moment you see one without the colour put it back to the original tank to try and keep only genetics of the red trait going in their own tank. If it's genetic this should work well to encourage that trait. I believe something was done to get some of the Ramshorns morphs. 

Also to feeding colour enhancing foods may also be a great way to keep the colour levels stronger and encourage it.

Pretty much keep it like shrimp to keep a strong and nice red you take out the shrimp that aren't showing as nice a colour and just keep "stronger" desired genetics

Pretty cool! I really like it if it works out for you that would be awesome! 

Best of luck!