Maintaining the pH

I was reading that you can add dolomite lime to the mix so that you never have to worry about the pH. I don't really wanna pay out for it so i heard an alternative is powdered egg shells, is this correct? If i add it to the mix then sprinkle it on top?

Thanks.

Dolomite lime is not always the answer, you can read a great little article on the subject here

regards,