That's about 27 ppm FC added which should be good for a CYA level up to around 70 ppm. With that amount of algae in the water, it'll probably consume the chlorine very quickly requiring frequent additions. If the pH started out at 7.5, then even after the chlorine addition the pH due to the dry acid will be around 6.6 or so (if the TA is around 100 ppm). The added acid drops the TA by around 26 ppm.
The pictures of this mess getting cleared up should be very interesting. Lots of brushing and filtering/backwashing/cleaning. And all of this could have been avoided with just a little chlorine added every week or two (assuming the water was cool and the pool covered). I guess some pool owners just don't mind paying someone else to clean things up.