grit & oyster shells

Are you suppose to give pigeons grit? If so, what brand is the best? Does grit contain oyster shells too? And if not, should pigeons be given oyster shells?

I have been using a mixture of: broken granite, broken oyster shells, broken brick, charred wood, magnesium carbonate (athletic chaulk), and pick stone. Now that most of the birds have babies, they are really eating a lot of the grit. At times, they are going for the grit before the food.

So I just took a bird class & learned that grit with oyster shell is now considered toxic because of ocean metals. I can't find any grit without the oyster shell. This is my first pigeon - she's about 2 1/2 mo. She eats 50 percent Harrison's pellets, & 50 percent grain mix. The grain...

I found a local farm supply store that actually stocks pigeon stuff. I am going in the morning to get crushed oyster shells and grit. They stock Bay-more Red and Grey Grit. What (besides the color) is the difference in the two grits? Should I be leaning towards one or the other? I have...

Oyster shells & Grit, can you mix them? How do you all mix it and or use it? I would also like to know, can Oyster Shells be use in place of grit or should they have both?