Yes there are many reasons. I had zero chlorine when I first started with my pool as well. The advice I got was very helpful, but so was the pool care basics. The advice I received was to first make sure you don't have any algae eating all your chlorine. Check out the section on running an overnight FC loss test and go from there. For me personally, getting CYA in range was the key. The pool company recommended like 30-50 CYA, which is where I was at, but turns out is should be way higher, otherwise the sun evaporates all the chlorine out of the pool. For the first 3 weeks I was only managing chlorine in my saltwater pool by pouring in liquid chlorine. I was thinking to myself..."what is the point of a saltwater pool if I am just pouring chlorine in every week". Once You rule out algae, then get CYA, pH and alkalinity in appropriate range, as recommended by TFP, then things go smoothly.