Hi Dizzle,
A CYA of 50 is going to be MUCH easier to deal with than it was, so you'll find that all your hard work was worth it!! So now you need to up your chlorine just a tad, because with a CYA of 50 you want to keep your chlorine between 3 and 6 ppm at all times. I'm referencing this table that we use as a guideline for chlorine amounts for algae-free pools..... (better known as Ben's Best Guess Table)
Stabilizer . . . . . . Min. FC . . . . Max FC . . . 'Shock' FC
=> 0 ppm . . . . . . . 1 ppm . . . . . 3 ppm . . . . 10 ppm
=> 10 - 20 ppm . . . . 2 ppm . . . . . 5 ppm . . . . 12 ppm
=> 30 - 50 ppm . . . . 3 ppm . . . . . 6 ppm . . . . 15 ppm
=> 60 - 90 ppm . . . . 5 ppm . . . . . 10 ppm . . .. 20 ppm
=> 100 - 200 ppm . . . 8 ppm . . . . . 15 ppm . . .. 25 ppm
Note that since you're on the high end of the 30-50 range, I would encourage you to try to target the next higher chlorine ranges, just to make sure--meaning I wouldn't let mine drop below 5 ppm, and would probably target 5-8 ppm for daily chlorination. In an 11,500 gallon pool, each 3 1/2 cups of 6% bleach will raise your chlorine by 1 ppm, so you can use that as a guideline to figure out how much you need to add each day.
Your alk isn't too bad at 120, so I wouldn't worry too much about adjusting it unless you're finding that your pH won't stay stable. If you need to adjust it, you can find the process stickied at the top of the "Alkalinity and calcium" part of the forum.
Janet
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