Replacing old reagents in Taylor test kit

Do they all need replacing every year or does storing them in a mild dark location make a difference?

I need to order some CYA test reagent i am completely out of that.

Does the DPD powder go bad?

When you start doing the math, if a majority of them need replacing, it almost makes more sense to order a new kit!

Thanks!

You do not need to replace every year. And, you are right. Storing them in a cool, dark place does help to prolong the life. DPD eventually does go bad. You will be able to tell. It will get gray and clumpy.