Persistant algae growth

First some background: 18x36 vinyl liner with 4' average depth, Pentair cartridge filter, build date August 2003. Full sun exposure in the mid-south USA. I try to follow dosage for a 20,000 gal. pool.

Latest test results using Taylor K1004 kit: Cl = 16 (using dilution method), ph = 7.2, Ta = 180, CA <= 30,
water temp 85 deg.

CYA test done with AquaCheck 7 way strips, is usually same result as pool store test.

What I have done this week:
1. Added 2 lbs granular chlorine (70% regular chlorine) twice this week, 4 lbs. total.
2. added 7 lbs of 20 Mule Team in attempt to raise Ph, it was below 6.8
3. added 1/2 gal of Leslie's Instant Conditioner (CYA)

Last year I had a high CYA level > 100, probably as a result of 9 years of tri-chlor use without any water replacement other than normal evaporation. I went through the partial drain and refill cycle to reduce the level.
This season I have added CYA slowly, 1.5 gal. total of Instant Cond. above over several weeks to raise the level.
It's still not where I want to be, but I'm reluctant to do anything quickly where the pool is concerned.

Result: Water is clear and algae seems to have stopped actively growing for now. I will brush and vacuum this weekend.

My question(s): Does the TA level seem too high? It has never been this high before. I always have difficulty with the TA test as it is hard to decide when to stop adding acid drops. Until the green first turns any shade of pink\red ?

I don't want to always keep the Cl level this high, but without it algae grows aggressively. Will continuing to increase the CYA help to overcome this problem?

Thanks for the help.