Thanks for help!

[jfmorris]

I just want to thank you for the information in Pool School, and useful advice on this forum. A week into the BBB method and the pool is once again crystal clear! I'm coming off shock levels. Here are tonight's readings after a sunny day:

TC 10.0
CC 0.5 (probably less - just a SLIGHT pink tint that one drop took to clear)
Ph 7.5
TA 140
CH 170
CYA 40

I had read 60 last week, testing the CYA at night, and did it this evening out in the light outdoors. I now read right at 40, which matches what I expected to have after a 25% water change a week ago. I think lesson I learned is not to test in a kitchen with just overhead lights at 10pm! I think more ambient light helped me see the dot longer. Anyway, I shocked at a TC level of 18, thinking the CYA was 60. Oh well...

Question, do I want to shock longer to get that CC level to 0? No algae anymore, water is sparkling clean. I will probably backwash the DE out again in the morning.

Will the CC go to 0? Like I said, it was just the barest hint of pink before adding one drop to make it clear again. I've been shocking for about a week, but only had the TF-100 kit since Friday, and have seen the CC reading bounce between 0.5 and 1.0 most of the past few days. This is the lowest I've seen it, i.e. less than 0.5.

Thanks!

 

[Richard320]

You're welcome, and the answer is maybe.

Your pool is clear - there's part one completed
Your CC is .5 or less - there's part two completed
Have you passed the overnight loss test?

.5 CC or less is treated the same as zero.

 

[jfmorris]

You're welcome, and the answer is maybe.

Your pool is clear - there's part one completed
Your CC is .5 or less - there's part two completed
Have you passed the overnight loss test?

.5 CC or less is treated the same as zero.

Yes. Forgot to say that. I have passed the overnight test the past 2 nights. Night before last, I had a drop of right at 1.0 overnight. Last night I had pretty much zero drop between 9pm and 6am (it was 18.5 when I got up this morning).

 

[jfmorris]

Here's another question. My FC dropped from 18.5 to 10.0 during the course of a sunny day, with a CYA level of 40. The Pool Calculator is recommending a range of 3 to 7. If I leave here for work tomorrow with a level of 7, is it going to be 0 when I get home from work? I am just looking at the fact that it dropped 18.5 to 10.0 during the course of a sunny day.

 

[jblizzle]

It is a little more correct to assume you lose a % of the chlorine to the sun each day.
You dropped from 18.5 to 10.0 which is about 45% loss (pretty normal for a CYA of 40ppm).
If you leave it tomorrow you would have 10 * 0.55 = 5.5ppm left
Then 5.5 * 0.55 = 3ppm the next day.

If you start at 7ppm ... you would be around 3.8ppm the next day. You would then bump it back up to 7ppm ... so your levels would always stay between about 4ppm and 7ppm.

 

[duraleigh]

It's a percentage drop. If you started at 7, you will likely end around 4 ppm. I would siuggest elevating cYA to 50 ppm down in Alabama. That a lot of sun and I think 50 will reduce your chlorine loss noticeably.

 

[Richard320]

Here's another question. My FC dropped from 18.5 to 10.0 during the course of a sunny day, with a CYA level of 40. The Pool Calculator is recommending a range of 3 to 7. If I leave here for work tomorrow with a level of 7, is it going to be 0 when I get home from work? I am just looking at the fact that it dropped 18.5 to 10.0 during the course of a sunny day.

Not likely. You lose a percentage, not a fixed PPM per day. You lost about 45%. So if you leave for work at 7, you'll likely find it somewhere around 3.5>4ish. You'll just need to monitor it and learn its appetite.

 

[jfmorris]

Ok - thanks for all the answers. Makes sense that it is a percentage loss, versus a straight loss.

I've got some granular Cyanuric acid that I can put in a sock to raise it to 50. I think I will monitor it this week though, to see how it goes. I worked hard to get the CYA down from 60.

I also still have a couple of 3" tabs in the chlorinator that I could open back up, and use those up. That might boost CYA a little. I plan to remove the chlorine feeder and build a liquid chlorine feeder to take its place. Another reason to axe the old Rainbow feeder is that it appears to be dripping water along a joint in the body. Thankfully I plumbed everything in with 1.5" unions, so I can disconnect two unions and pop in a replacement section of pipe...