I have a 40,000 Gallon pool with a hayward NGS60 (60 Sq ft) filter. I recently had a quick algae bloom and being a kind of newbie with chemicals I used one dosage of Yellow Out, which is way under the recommended dose. I did everything it said added correct shock and what not. It was all doing fine until I noticed a weird smell. I checked the chlorine and it was at 0 and Total Chlorine was at like 0.3 or something like that. So the pool guy told me to shock and then a day later backwash. I did all that but then the chlorine was still low so I ended up adding about 9 pounds of shock in an hour without checking the CYA or knowing that the type of shock I am using has CYA in it. I also use Trichlor tablets in an in-line feeder. So now everything is back to normal, but im worried about this so called "Chlorine Lock".... Is this a thing or should I be ok doing what I am doing? I am soon going to switch to the BBB method. But I still have alot of Dichlor shock. Suggestions and ideas please.