Ok. Same advice as in post #2 above. Since you had CYA of 40 and none now, you are going to probably need to add bleach a couple of times per day to maintain shock level. And, since it appears your CYA biodegraded, I hate to tell you, but it may take a lot of bleach to get rid of all of the byproducts left behind. Keep at it!

(To save your testing reagents, use a 10mL water sample when running your chlorine tests instead of a 25mL one. Multiply the drop count by 0.5 instead of 0.2.)

Keep us posted how things are going.