[bikinibottom]

i've wondered the same thing. I thought my snails were darker originally but now they are a translucent pink/brown. Maybe this is just a normal color pattern for them as they mature? In more acidic tanks or tanks with CO2 injection could it be a lack of carbonate ion and they're making thinner shells? My tank has a pH of 7.3 and no CO2 injection so it kinda blows that theory out of the water, unless the snails normally come from waters with pH levels higher than that. Ca seems to be a possibility. A few other possibilities: light levels; types of food/algae they eat; stress....

Would be curious to hear if anyone knows anything about this.

 

[bikinibottom]

I have seen that, and, like you, I associate it with low mineral, low carbonate, acidic water.

You could try adding a bit of cuttlebone to the tank and see if the snails will crawl over it and eat it.
Cuttlebone will slowly dissolve in water, raising the GH and KH a little bit. It is very slow, and weekly water changes will correct this back down to where you want to keep the levels. MIght be just enough to help the snails.

My tank has pH of 7.3, a GH of 8 and a KH of 5 -- do you think these parameters are indicative of a tank that is too acidic and/or low in minerals/carbonate ions? I'm new to the freshwater world so I'm not sure how low a pH would need to be before it would start causing snail shells to thin.