I also wanted to thank you for your service. You guys are incredible!!

Just a comment to add to what Ben said--the reason you were able to maintain chlorine before was probably because you had a good stabilizer level. However, after an algae bloom, many times that stabilizer level will fall, and will not retard the sunlight consumption of your chlorine.

I agree that you shouldn't let the chlorine drop--assuming your CYA level is zero, then you should take the chlorine up to the 12-15 ppm range and hold it there until it clears up, or until you can measure the chlorine at night and again in the morning prior to the sun hitting the pool, and only lose 1 ppm or less chlorine overnight.(See the best guess chlorine page linked in Ben's sig for more on that subject.) It will help if you get a current stabilizer level, so you know where your chlorine levels need to be.