In order to have the best success with worm composting, your worm bin PH must be managed to ensure the health of your red wigglers. The easiest way to do this is to add garden lime or lawn lime (dolomite or pure calcium carbonate) every two weeks. This product is called garden lime, lawn lime or slow lime at farm supply and hardware stores. Do not buy slaked or hydrated lime, also known as quick lime. This product can kill your worms.
To maintain your PH, dust the surface of the bed with the lime and wet it down. The worms will consume the lime and excrete it all throughout your bin. Red Wigglers do best with a neutral PH of 6-7. Adding lime regularly will keep your PH within the correct range. Furthermore, worms need calcium which is provided in the lime to digest their food, and also to produce eggs. Over time worm bins will become acidic due to decomposition of added food scraps. Regular additions of lime will prevent this from happening and will keep your worm population healthy which in turn will create lots of high-quality worm castings for your gardening needs.