I now have both the Taylor and ColorQ test kits. ChemGeek sent me a standard 100 sample of ALK and the Taylor tested exactly 100 whereas the ColorQ showed 91. I mention this only to show that I believe I am doing the tests right. However, I am still getting bizarre results. I have been testing with both kits just to see what differences result, and not only are there differences in the kits, but the pool is simply not responsive to acid. I give the Taylor results first with the ColorQ results in parentheses.
10/10 (test 1): PH 8.2+ (7.8), ALK 110 (89). I wanted to bring the ALK down to the recommended level by reducing the PH to 7.0. PoolMath said to add three quarts (96 oz) of acid so I did so. This was labeled as 29% variety and is only a couple of weeks old. Waited 1-1/2 hours and retested.
10/10 (test 2): PH 7.5-7.8 (7.5), ALK 110 (81). PoolMath said to add 74 oz more to get to PH 7.0, but I only had 60 oz on hand, so I added that. By this time there was not enough time to circulate a full 1-1/2 hours so I waited until morning. Tested at about 10:00 after the pump ran a couple more hours in the morning.
10/11 (test 1): PH 7.2-7.5 (7.3), ALK 110 (77). PoolMath said to add 80 oz more acid to reach PH 7.0, so I added that. This was fresh acid labeled 31.45% that I got from Leslie's. It smells strong. Waited until 2:30 to retest.
10/11 (test 2): PH 7.2 (7.1), ALK 100 (65). PoolMath said to add 47 oz more of the 31.45% acid to reach PH 7.0, but I actually added 49 oz to finish out another jug. Pool ran about an hour but I waited until it ran a couple of hours this morning (i.e., 10:00) before retesting.
10/12 (today): PH 7.2 or more in that the color is still pinkish, not orange (7.3), ALK 100 (61).
According to the pool builder, the pool has 19,000 gallons. According to the construction diagram, it has 610 sf of area. I have measured it at 39.5' long and 17' at one end and 14' at the other. It slopes gradually from 3.5' down to 5.5', with about 700 gal in the spa and there is also a sun area that is circular and around 7' diameter with about 1.5' depth. These give me volume results greater than the pool store, but not a huge amount greater.
At this point I have put 2 gallons and a quart of acid into the pool and never yet achieved a PH of 7.0. Granted, I have a hard time reading the Taylor PH test but even the ColorQ has never reached 7.0. Moreover, the ALK has dropped a less-than-whopping 10 from the starting point according to the Taylor test. Even with the ColorQ, it isn't much of a drop in ALK considering how much acid has been added. It is incredible that the PH actually rose last night even though I put 49 more oz of acid into it. Nothing else has been added to the water other than a little from the feed line -- which Taylor shows has a PH of 7.5 and ALK of 160. Really there shouldn't have been very much feed line water going into the pool in the last two days anyway, considering it's cool here now.
These results should be chemically impossible, right? How the heck can anyone add over 2 gallons of acid to a pool of this size and still have PH over 7.2 and ALK barely changed. For that matter, how could PH actually RISE overnight after adding 49 oz of acid??? The only thing I can think of is the spillover from the spa due to the in-floor system, but it really only spills over for about 5 minutes at a time for a couple of times an hour. For a long time it has sat at PH 7.8 and ALK in the 90s (according to the ColorQ, anyway). I never saw the PH go over 7.8 with the ColorQ whether I added acid or not.
Any ideas what is going on here? I am beginning to think it is impossible to reduce the PH and ALK in this pool.
FYI, the last full test of the pool water was also on 10/10 and showed this:
FCL: 5+ or 7.5 using the "better" Taylor test (5.17 on ColorQ)
CH: 400 (232)
CYA: 37 (39)