New owner - TFP method and testing questions

Go_Bluewater

Member
Aug 22, 2023
6
Ann Arbor, MI
Pool Size
19000
Surface
Fiberglass
(Preface: I’ve now read pool school, ABCs of water chem and have a K-2006 on the way)

Hello all, I am a newer owner of a 19,000 gallon fiberglass pool that’s about 15 years old. I had it at the end of last season, it was open for maybe 6 weeks, went to the pool store for testing, and used strips, no issues.

This year I was lax on testing (didn’t know I was supposed to test daily) and have been feeding 3” tabs. The pool has been crystal clear, I’ve been skimming daily, brushing and vacuuming weekly, “shocking” with a gallon of liquid on Sunday night after weekend swimming and it’s been a great summer.

The pump bearing went bad, so there was no pumping for four days. After the pump was replaced I took a sample to the pool store for testing. They said I had no chlorine and extremely low TA. (A little odd, my strips were blazing purple and the feeder always has three tabs) After three trips I was told to add 30 lbs of baking soda (12, 12, 6) and four gallons of chlorine. The pool went extremely cloudy, slightly greenish/yellow. I vacuumed and backflushed several times, it started clearing but not like before. There was dead algae at the bottom I’d vacuum to waste.

The last week has been a whirlwind of weather, 8 inches of rain, tornados, it’s been crazy. After cleaning the pool and vacuuming excess water to waste it’s looking crystal clear again, but chlorine levels still seem extremely high. I’ve cleared out the feeder of tabs.

I did a deep dive of TFP, the quickest test I could get is the K-1004. Standard OT test is off the chart. 2:1 dilution is off the chart. 3 parts bottled:1 part pool shows maybe a little more than 20ppm of FC. TA bleaches out. Using an extra drop like Taylor recommends gives TA = 90ppm. pH is about 7.4. I have the K-2006 arriving today which I’ll do the full range of tests and report back.

Does it seem safe to swim now? Is it safe to use the heater?

Does it seem strange that the chlorine level would still be at 20+ppm 5 days after adding chlorine? Could the CYA just be through the roof preventing breakdown of it?

After the K-2006 tests I think I’ll have a roadmap. Long term, is there any method to chlorinate without having to add liquid daily that doesn’t blast CYA? I kind of have one foot in pool store and one foot in TFP at this point mentally.
 
Ok, I’ve taken the K-2006 test results. CH is very hard to read, it goes faint but not really sure if it is clear. CYA is also really subjective, my wife and I both read it the same.

FC = 38.5
CC < 0.5 (it turned barely pink but cleared with one drop)
TC = ~38.7?
pH = 7.4
TA = 80
CH = 330
CYA = 100
 

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Did you do an extended test on your CYA level? Dilute the pool water 1:1 with tap water. Use that for your sample in the CYA test.
Double the result.

You likely will need to do a water exchange. Read Draining - Further Reading
Ok, I have done the 1:1 dilution, I get right around 50ppm with the diluted, I did it 4 times. So 100-110ppm on the pool is where I am.

FC is at 33.5ppm. Thank you for the link on partial water replacement, it is very detailed which I appreciate!
 
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