Need advice. test results and strange happenings this week

Apr 10, 2011
17
I opened my pool here in Alabama in March and quickly turned the green 14000 gal pond clear blue and have had no issues until we got rain for a week straight last week. I had a day when I checked the FC level with my Taylor 2006 kit and it was 5, so I didn't add more bleach. Then after a rain it went pretty cloudy. On 6/26 I shocked it to a 12. When I tested my CYA again on the 27th it was less than 20 - after being about a 35 before. So I decided to add a bag a dichlor shock to get the CYA up a little and reshock the pool. It was still cloudy and had a lot of browninsh sandy like stuf on the bottom, which vacuumed right up. On 6/28 in the late pm my FC was a 5, CC =0, pH 7.6, Alk = 90, and CYA less than 30 (maybe 25). I decided to not add any bleach and do the overnight chlorie loss test. It was at 4 the next morning, with CC =0. I thought great! I have nothing and am at an acceptable level for FC and CYA, but then I checked the FC the night of the 28th and it was a zero!! I haven't seen it do that before. the water looked better. When I tested the CYA again to see if the dichlor had raised it, it was a 40. Fearing that something was a work with the 0 FC level, I decided to use the pool calculator and add enough bleach according to the pool calculator to shock raise the FC to a 16, the recommended level for CYA of 40. So I checked the FC level on thur 6/30 and it was a 19. How was it higher than what the pool cal. said it would be? huh...

Then I waited till 9pm last night and tested again. FC was a 4.0 And the CYA was under 30 again. What is happening to the CYA? How was it a 40 then under 30 with no one being in pool splashing or no backwashing? I added 29 oz of bleach to raise the FC to a 5 and checked this morning. The FC was a 6.0. Again the bleach is having a bigger rise then the calculator says.

So, there is my background, but I am still concerned. We are having some 96 plus heat direct sunlight days on he pool and my chlorine is dropping. I was shocked to see my FC drop from a 19 yesterday to a 4 late pm, Then the day before recall that it was a zero. Here are a few questions for you experts:
1. My speculation is I need to add more stabilizer for the the CYA to climb and keep the chlorine in the pool on these super hot days? Does anyone agree? What level would you aim for in the hot sun - maybe a 35-40?
2. Would you just add to a sock and leave it running the whole weekend?
3. Why do you think my CYA is fluctuating b/w tests?
4. I will be gone on vacation next week, so I am trying to get the pool in good condition to leave it. i will have someone to add bleach each day, but I need to get it consistent to know what for them to add. For 2 months, I could add 60 oz and the FC would go from a 5 to a 3 every day like clockwork. Should I have them add some extra each day just in case?
5. Would it be a bad idea to use some of my 3'' trichlor pucks that I have left from last year to add some stabilizer and to chlorinate the pool while I'm gone and can't watch it and test it?
6. I'd love for someone to explain what adding a 1 lb bag of dichlor shock is supposed to do for my 24' by 52'' (about 14,000 gal) pool. How much will it raise the FC and the CYA level per bag?
7. Same question for adding one 3'' puck. What will it do to the FC and CYA for my pool?
8. Sorry for all the questions. I thought I had this figured out with no problems since april, then this week has me puzzled. If someone can explain the previous I think I will be prepared for future problems. Any other comments or suggestions would be appreciated. I am a chem teacher, so feel free to get technical if you wish. I'm interested in how it all works. Hope to hear from someone today and get a jump on my CYA issue that I fear may be causing the issues I see.
 
Re: Need advice. test results and strange happenings this we

How are you testing? It sounds like you might be using test strips, which give variable and inconsistent results, especially for CYA levels.

1) The ideal CYA level is anywhere between 30 and 50. Since it is early in the season, closer to 50 is good.
2) Yes.
3) Bad test results.
4) Yes, extra bleach is safer.
5) That could work.
6&7) You can use the Pool Calculator to figure out things like that. See the Effects of adding chemicals section towards the bottom.

Remember, chlorine needs to be added every day.
 
Re: Need advice. test results and strange happenings this we

One thing is that your pool isn't 14,000 gallons, in fact, it isn't even quite 13,000 gallons but that's close enough for the Pool Calc.

1) I keep my CYA at 60 ppm and am north of Mobile.
2) No. See No. 5.
3) The variability of the test is ±15 so what you're seeing is basically the same number.
4) No, just have them use the OTO kit ot make sure there's some in there.
5) That's a good idea. I stick a floater in the pool and have it checked every few days.
6) You can use the Pool Calc to do that. There's a section near the bottom that figures the effect of adding chems. Addig 1 lb of Dichlor will raise your FC by 5 and your CYA by 4.5.
7) Depends on the weight of the tablet. They're different sizes. See #6.
8) See above. :)
 
Re: Need advice. test results and strange happenings this we

Thanks for the input. I am using the Taylor Fas-PDF 2006-k kit. I am going to assume that is is about a 30 and leave 1 puck in the skimmer and 2 in the floater. that should raise my CYA by about 6 and help with the chlorine while I'm gone. Maybe add a little stabilizer (9.0 oz) this weekend to aim to get my stabilizer level up to 35 to 40 when I return.
 
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