A well maintained worm bin should have a pH measurement between 6.0 and 7.0, which is perfect for many types of composting worms. Most can handle pH conditions up to 8.0, but its always best to play it safe and try to maintain a pH in the 6.0-7.0 range. The easiest way to do this is to add a handful of lime mix into your kit every couple of weeks. Don't worry about over liming as your lime mix is a mix of calcified lime and fibre rather than conventional garden lime which is too strong.
Basically to ensure your kit isn't too acidic look out for the signs of acidity - these are flies being attracted to the kit, a putrid smell, a really wet kit, or sometimes even swollen bits all over your worms (which is protein poisoning). If you see or smell any of these issues just add a few more handfuls of lime mix - add crushed egg shells for a similar affect and all will be well.
For more help with Worm Composting please visit our Wiggly Wizard knowledge base here https://wiggly-wigglers-faq.malcolm.app/
Or if you want more info about purchasing a wormery or starting worm composting please pop on over to