Mystery snail turning white

[andyb]

I got a mystery snail a few weeks ago. It was a light blue color. Now it's shell is starting to turn white. It started by its head and is slowly moving down the shell in almost a perfect line. Ive read in a few places that this could be a calcium deficiency. I added some spinach on Saturday then my nitrites spiked so I removed it and did a water change. Then I bought some wonder shells thinking they would boost calcium but didn't realize it would raise my gh as well. My water is already at 150gh so I am apprehensive to add the wonder shells. Thoughts?

Current numbers

Nitrate: 10 ppm

Nitrite: 0 ppm

GH: 150 ppm

Kh: 120 ppm

pH: 6.8

CL: 0

 

 

 

 

 

 

 

[Guppysnail]

The white is new growth. There was probably something in the tank they were eating or some type of algae growing on its shell that caused that blue. 
Its new growth looks very thin. Spinach is not your best option. The iron in it somehow binds the calcium.  Things like Zoomed nano banquet blocks and calcium chips are good edible sources of calcium. Folks like myself and  @Chick-In-Of-TheSea also make their own foods containing edible calcium. 
Shell erosion is caused by lack of calcium in the water. Thin shells are lack of dietary calcium. 

[Chick-In-Of-TheSea]

In my signature line below is a care sheet.