With a CYA of 110, he is going to need a lot of chlorine to prevent algae. Since he has visable algae, you will need to shock and keep the level up until all algae is gone. With that level of CYA, chlorine wil have to be maintained around 10ppm with a shock level of around 25.
The reason the CYA level is so high, is because he is using Dichlor for his chlorine source.
He should be using unstabilized chlorine from this point. Most of us here use standard bleach...sodium hypochlorite.
Also, you will need some borax to get the pH up