New kit owner and I tested my brother's pool

Took my 234 test kit over to my brother's 16 x 32 inground (18,000gls) vinyl pool and here's what I got......

Water is crystal clear, traces of algae visible.

FC 0.......(out of town for week nobody added chlorine):ma:(
CC 0
TC 0
pH 6.6
Alk .....Turned red immediately?
CYA...110

He has been using sodium dichloro-s triazinetrione dihydrate from Sam's Club I think. Available chlorine 55%

I added 2 cups of this to bring up cl level.

What else do I need to tell him to do?

Sand filter running 24/7.


Thanks!

PS I'm in the process of converting him to the 3 B's!

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

Get the pH up sooner rather than later...Borax...start with one box and retest.

Recheck your testing method for Alk....something's probably not correct. If Alk is truly 10, you'll need some baking soda (lots) but get your pH up first.

Shock and then maintain Cl per azimmer's recommended levels.

Thanks!
I'll get pH up and have him shock with bleach..