Trichlor tabs would be ideal right now -- they add chlorine; add stabilizer, and lower the pH! You can just add them to your skimmer, till you're able to maintain your FC that way. The only caution: if you use a pump timer, the chlorine level can get VERY high in the skimmer. Ideally, you'll run your pump 2x per day, to prevent that. OR, you can use floaters.