Yes - you do need cya. But, in the meantime, you are going to have to maintain a chlorine reading or you will have a green pool. It will be a pain for a few days until your cya dissolves and you begin to get a cya reading because in the meantime, your chlorine is going to disappear pretty quickly - especially on sunny days. Nevertheless, you do need to maintain that chlorine level. It may require you to add quite a bit of bleach for the first few days. After you get a cya reading, you should just be able to dose with bleach in the evening. Remember, when adding cya, add it to the skimmer with the pump running and then don't test for it, add more or backwash for about a week to give it time to dissolve. Otherwise you may end up with more in there than you want. Hope this helps.

Watermom