I would suspect that you are having trouble raising your FC for several reasons, some of which are 1) you are still on the edge of an algae bloom, since algaecides (and here we only recommend polyquat) are much better at preventing algae than killing it, therefore it's consuming the chlorine as quickly as you put it in, 2) your algaecide is creating its own chlorine demand in the pool, and 3) with a low CYA you're losing a lot to the sun. In order to clear it iup, you are going to have to get the chlorine up to your shock level (as they said above, that's based on your CYA level, so you need an accurate one to start with)--see the "best guess" link in my sig for more info about that--and keep that chlorine level up until you stop losing chlorine when testing at night and again in the morning before the sun hits the pool (that measures how much chlorine the pool is using and rules out what the sun is consuming). Only then can you let your chlorine drift back down--but how low you can let it go also depends on that same CYA level. So....you're gonna need a test kit to accomplish this, but it can be done with the cheap OTO (uses red and yellow drops to measure chlorine and pH). However, if you can invest in a good, comprehensive kit, it will pay for itself over and over and make your life SO much easier!!