Pool PH Suddenly extremely high (maybe)?

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T

tre

0
Dec 4, 2007
12
Barrington, IL
I maintain my own chemicals and have for many years. I've never had an issue. I use a pool company for opening and closing and normally ask them not to put any chemicals in. Today they arrived to close the pool and misunderstood my request for no additional chemicals. Something they did caused my PH to go from 7.4 to 9 or even 10 (maybe).

Numbers as the pool company pulled up:
FC - 11
TC - 11
CYA - 60
PH - 7.4
TA - 90
Salt - 3600
Calcium - about 600 (very high calcium well water from auto fill)
Pool is 26,000 gallons

My plan was to slam the pool after they drained out some water and before they put the cover on. I was talking to one of the guys who was working on the pool heater and when I turned around, another guy dumped in 2 bottles of GLB algimycin 600 (algicide). GLB Sequa-sol (Sequestering agent?), and pool magic (no idea what this is). I never use anything other than stabilizer in the spring, muriatic acid to bring the PH down, and liquid chlorine when I need to supplement the salt cell. I add salt in the spring too. I've never needed any of these others items they dumped in.

After they dumped these items into my pool, the PH test now turns a very dark purple as if the PH is 9 or 10 (off the chart). I am 100000% sure the PH was 7.4 when they arrived. I use a Taylor K-2006 test kit with refills from TFTestkits. Could one of the items they dumped in cause the PH to spike or the test to give a false reading? I double checked the chlorine and they did not add any more chlorine so it is not a case of very high chlorine washing out the PH test. Could the PH suddenly be 10 from something they did? I don't want to dump in acid if it is not needed and cause the pool to be too acidic. I have not added more chlorine because I know it will simply destroy the algicide and in turn cause combined chlorine. Any advice for this mess would be helpful. Should I add acid? When should I slam since they added all this stuff which the chlorine will just break down if I slam and it will defeat the purpose of the slam. Thank you!
 
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Tested again. FC is now 9 and CC is now 1. I don't have a PH meter, only the Taylor PH test which is included with the K-2006 test kit (I'm using the R-0004 reagent to be specific).

I took a bucket of pool water and added a tiny bit of PH up to it to see what would happen. Same result. Purple PH test. I cleaned the bucket and did the same thing but this time added two drops of muriatic acid to the bucket. Below is a video of that test. It look like the PH was 7.0 after I added the acid but then the test washed out to purple again. Something they added seems to interfere with the PH test. As far as I know, they added 2 bottles of GLB algimycin 600 (algicide). GLB Sequa-sol (Sequestering agent with possible phosphate remover in it too), and pool magic (some sort of enzyme).

PH test video:
 
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The pool magic product SDS says the pH is close to neutral, so it seems unlikely that it would have raised the pH substantially. The active ingredients listed (they don't have to list everything) are a detergent/wetting agent and a corrosion inhibitor. There is no mention in the SDS of any enzymes, but these are generally very sensitive to pH so it's unlikely that they would formulate an enzyme product with a high level of alkali. The corrosion inhibitor also sees some use in dye and printing ink formulations and might have some potential to cause colorimetric interference. The algimycin is just a polyquat algicide. I don't generally use those, so I don't know if a high dose would interfere.
 

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Tested TA again. TA = 60. TC remains = 9. Added two drops of R-007 and tied the PH test again. It did not wash out this time and read 7.4. Tried the PH test again without adding R-0007 and it turned purple so it is clearly the chlorine level washing out the PH test. This baffles me because this has never happened at a TC level of 9. Is it possible something they put into my pool is contributing to this? I'm baffled.
 
That TA is a total mystery to me. I checked it twice. I don't know how it could fall that much. My fill water is very high TA and my auto-fill has been adding water daily (no rain here). I can't imagine how it went from 90 to 60. I've never seen that happen before. Thanks for your help and advice. Will get all new reagents in the spring. Mine are clearly getting up there in age.
 
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TA is the second trickiest to the CYA test. You can have static on the tip even when not new but especially when new and needs to be wiped with moist paper towel between drops which means inverting each time which can grossly contribute to error when not perfectly upside-down waiting for the droplet to fall off while maybe not holding it comfortably. You'll need more smaller drops to achieve the same results with fewer larger droplets to achieve the same color change.
 
+1. And if you don’t have one already, the smart stir is worth it’s weight in gold. Hands down the best $30 you can spend on your pool.
 
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