How are you testing?

A reading like "alk=112 ppm" looks like a computer read test strip. Test strips do NOT allow accurate readings of chlorine, and provide horrendously inaccurate readings of CYA.

What is the OTO test result? Have you ordered a K2006 . . . or purchased a local HTH 6-way kit (contains the Taylor CYA test)?

If you've been adding 2 gallons 2x per day, on 17,000 gallon pool, and are still "blue-green", you need higher chlorine levels. Continue with the 2 gallons in the AM, but go to 4 gallons in the late PM . . . and TEST WITH OTO!!!!