Best case: 72 oz (4.5#) of "granular chlorine" is either 62% dichor or 65% cal hypo, and you've 4.5# of shock and 2.7# of chlorine equivalent. On a 12,000 gallon pool, that about 27ppm. That *may* be an effective shock level *if* (and only if) your stabilizer is below 100 ppm..
Worst case: you've got goop shock that's say, 20% chlorine equivalent AND you have 120 ppm stabilizer, so you've add only 9 ppm of chlorine to pool that needed 30 - 50 ppm repeatedly, to be effective!
What you need to know: shock doses that aren't effective, are essentially a complete waste.
And your question: a phenol red test result, where the sample remains a color similar to the original has a pH ~ 7.6.
But, do this:
#1 - Take your pool water to a couple of pool stores to be tested, and see if you can find out what your stabilizer level is. If two stores agree, there's a fair chance that that is a meaningful and somewhat accurate reading.
#2 - Meanwhile add shock OR plain 6% household bleach UNTIL the OTO (yellow side, clear drops) gives you a dark yellow / orangish reading . . . and then keep dosing to MAINTAIN that level of chlorine . . . no matter how much you have to add. With bleach, 5 gallons of 6% bleach is a reasonable starting dose for your pool.
#3 - While at Walmart getting bleach, ALSO buy 1 gallon of plain *distilled* (not: bottled, crystal, spring, natural, etc) water. While your chlorine is high, mix your pool water sample 50:50 with distilled water and then test the mix. This will still give an accurate pH results, and will keep the chlorine from messing up your test. (Collect 1/2 cup of pool water; pour it into a large glass container. Add 1/2 cup of DISTILLED water & mix. Fill your test kit with the mix, and test pH. Do NOT test chlorine this way!!)
#4 - Read the "Best Guess" page linked below.
#5 - If you really want to get control of your pool, order a K2006 test kit (Amazon links below), so you can get accurate test results for chlorine and stabilizer -- 'guess' strips are NOT accurate enough, especially for stabilizer results.
#6 - Report back once you have some sort of information regarding your stabilizer level.
Good luck!
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