To be able to help you, we are going to need some good current water testing results taken with your K-2006 kit. If you can't hold a FC reading, I am wondering if you have had a high CYA reading in the past that has biodegraded and left you with a pool full of ammonia. A symptom of that is the inability to hold a FC reading.

Also, if the sides are slippery then you have an impending algae bloom. Adding little bits of bleach is not going to solve it. It is going to have to be taken up to shock level. But, we can't know what your shock level needs to be without knowing your CYA reading.