the best thing to do would be lay off the eggshell, which is what's making the bedding tend toward alkaline, and will likely make the castings heavy on calcium, which isn't necessarily a good thing ... altho 7.5 isn't a problem, 6-7 would be what would happen naturally, there's no need to "control" the pH in composting, the process takes care of it ... the decomposer bacteria prefer a slightly acidic environment, microbes being the worms primary food, and their activity tends to result in a neutral end product ... also the worms don't need a steady supply of grit once the system is established

Bill

Great. I'll stop with the eggshells an see if things balance out. Thanks for the info!

What are you using for bedding? Some bedding tends to be more acid and requires the extra egg shells or lime to adjust it for the worms but if your bedding is neutral and the overall conditions have become higher on the scale then perhaps mixing a little of a slightly acid bedding might help balance it for you.

I'm using shredded newspaper for bedding. What would be a more acidic bedding material?

Newspaper is generally slightly acidic but only slightly. Peat moss is a very acidic bedding but most people don't use much because of the cost and other possible negative atributes.

You are probably just fine cutting down on the egg shells.