John, Any time you add manure, compost or the like into a SWC you are defeating the wicking action. Keep it up and soon you will have a bog that does not wick at all. =( Eggshells, even powdered take forever to break down. The reason we use dolomite lime is is helps defeat the acidity present in the peat moss. Even dolomite takes several months before it is fully available to the plants. I have never used eggshells in a SWC, atleast not that I remember, and my memory isnt too good anymore either! LOL LInda

2 cups of pellets is not going to make that much of a dfference in the wicking. years of reusing the soil would have a problem. as for the rest what linda said.

Dolomite (garden lime) is less than $ 6 for 40 pounds

Thanks for the help. Can you suggest where I might get bulk dolomite? I have only seen it in small packages.