TF 100 is here. Test results. What now?

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S

Strobos

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LifeTime Supporter
Jun 21, 2012
17
Phoenix, AZ
Following up on my post from a week ago. The pool was drained, scrubbed with bleech to get rid of algae including mustard. Pool was filled and shocked. CYA was calculated and added.

The TF100 came in Thursday afternoon. Here are yesterday's and today's results.

Yesterday. FC 2, CC 0.5, pH 8.2, TA 210, CH 220, CYA 20.
Based on the pool calculator, I added 39 flozs 14.5% muriatic acid and 65 flozs of 10% bleech.

Today. FC 5, CC 0.5, pH 7.8, TA 210, CH 220, CYA 20.
I have reservations about my TA and CYA results. Leslies has tested my water 3 times before. On 7 May, TA was 120 with a pH of 8.0 May 3 they got TA 150 with pH 8.0. May 1 TA was 100 with pH 7.6
I was extremely thorough with my testing so I don't know why my TA results are high two days in a row. The same with the CYA test. I was seeing the black dot when my wife couldn't. Leslies last CYA test was 45.
What should I do about the high TA? and should I ignore my CYA results?
Thanks everybody.
 
Check out this link for images on the correctly performed CYA test:
http://www.taylortechnologies.com/ChemistryTopicsCM.ASP?ContentID=36

Wipe the tip of the TA dropper bottle between drops with a damp cloth and see if that changes your results. High TA only means the PH will creep up. IF it creeps up to 7.8 you simply use Muratic Acid to lower it to 7.2. Eventually the acid lowers the TA into range and the PH drifts slows/stops.
 
Strobos:

I would trust the results of the TF-100 test over the pool store's results. The CYA test is perhaps the most subjective test to perform. Lighting is critical. I perform this test in bright midday sun. After mixing the CYA reagent with the sample pool water as directed in the kit, I hold the view tube at waist level with my back to the sun and pour in the reagent/pool water mix. You can take an initial reading and, if desired, repeat the test by pouring the reagent/pool water mix from the tube back into the mixing vial and re-pour into the view tube.

The high TA can be reduced with muriatic acid (MA) following this procedure: http://www.troublefreepool.com/pool-school/lowering total alkalinity
 
Poolmom, I was doing the CYA in the bathroom with good lighting, maybe too good. I was wiping the bottle tip with a paper towel, not a rag. I read today that the purpose was to get rid of static electricity. Maybe the rag works better. Tomorrow, I will do it outside like you do using a rag.

Bo, I am thinking that dropping the pH from my present 7.8 to 7.2 is is too big a drop. That's a lot of acid to add at one time. Would it be better if I did a 2 step or even a three step process then follow the TA instructions you linked?

Thanks
 
Strobos:

There is no harm in reducing the pH from 7.8 to 7.2 all at once. The bigger issue is how the acid is added to the pool. The article addresses acid "slugs" which is basically undiluted acid indiscriminately poured in one or two isolated spots within the pool. That causes a very high concentration of acid in those areas, so you definitely want to avoid that. The pump should be running when you are adding any chemical to the pool. The way that I add acid is by measuring out the appropriate dosage in a large measuring cup and then dilute it with a little pool water. Then I pour the mixture in front of a return jet very slowly with the pour spout of the measuring cup an inch or two from the water surface. As for how I define slowly, the amount being poured from the measuring cup should be about the width of a standard pencil.

With that said, you could try reducing pH in smaller stages - there's no harm in it. However, it will take longer to achieve the desired TA that stabilizes your pH drift.
 
I am convinced. I'l do it Tuesday on my day off. Pool calculator says I need 1 gal + 3 quarts of 14.5% to get it to 7.0 pH or 1 gal + 1 cup to get 7.2 pH.
Which would get better result? or split the difference and go for 7.1?

Thanks
 
What bad things happens below 7.0 pH?
Click to expand...
As the pH lowers below 7.0, the water becomes more and more aggressive and can begin to damage equipment...particularly pool heaters.

It is not like you are perfect at 7.0 and the pool catches on fire at 6.9, it is just that 7.0 is a nice, safe bottom guideline which should be pretty closely adhered to.
 

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