I am having an issue keeping chlorine in my pool even after shocking to above 20 it is gone the next day. I normally use bleach as my chlorine. I tested the CYA level yesterday and it is about 5 which I think is the issue. What do I use to bring my CYA level up? If I start using chlorine pucks will that help or is there a way to add stabilizer?

I have a 23,000 gallon in ground rectangular pool with a vinyl liner

Thank you in advance.