chlorine at night, need to drain pool?

[irvinenewbie]

Here are a set of new numbers from today:
pH ~7.5
FC 6.5
CC 0
TA 100 (using 10ml sample dilution method)
CH 350 (using 10ml sample dilution method)
CYA 60
water temp 75F

I added enough 6% bleach to raise FC to 8.5. Everything else is within range except for CYA. But overall numbers look good? Do I keep pH within normal recommended range now (instead of below normal)?

2nd questions is: going away for vacation for one wk. Any recommendations?

BTW, the acid odor was in the soil after it rained. It's much less now, but I have no idea what the source was.

Thank you.

 

[polyvue]

Here are a set of new numbers from today:
pH ~7.5
FC 6.5
CC 0
TA 100 (using 10ml sample dilution method)
CH 350 (using 10ml sample dilution method)
CYA 60
water temp 75F

Q. What's wrong with this picture?

A. Not a thing... :-D

I believe the reason for wanting to maintain a slightly lower pH range was to accomodate higher chlorine so that you could lift a deep-end stain (this presumes an organic stain... not metal.) Though the recommended level is 7.5-7.8 you can easily get by with 7.3-7.6 if you prefer.

Determine how much chlorine and muriatic acid you add on a daily basis. Try to anticipate both acid and chlorine demand for that week; right before you leave, adjust the pH and chlorine with enough of the chemicals to make adjustment unnecessary for 7 days.

 

[duraleigh]

TA 100 (using 10ml sample dilution method)
CH 350 (using 10ml sample dilution method)

I've thought about it for a while and I can't figure out what that means. What did you dilute?

 

[irvinenewbie]

Determine how much chlorine and muriatic acid you add on a daily basis. Try to anticipate both acid and chlorine demand for that week; right before you leave, adjust the pH and chlorine with enough of the chemicals to make adjustment unnecessary for 7 days.

What if the amount need to be added will put pH way low for the first few days after addition? FC way high is a plus! semi shock.

TA 100 (using 10ml sample dilution method)
CH 350 (using 10ml sample dilution method)

I've thought about it for a while and I can't figure out what that means. What did you dilute?

This is according to PaulR's notes below. I clarified the method used to account for any accuracy/precision discrepancy, if any. Wanted to save reagents since my anticipated TA and CH are high.

Total Alkalinity Test
Use quantities in [brackets] if TA is very high.

1) Rinse and fill sample tube to 25ml [10ml] mark.
2) Add 2 drops [1 drop] R-0007; swirl to mix.
3) Add 5 drops [2 drops] R-0008; swirl to mix. Solution should turn green or blue.
4) Add R-0009 one drop at a time, swirling continuously, 1-2 sec between drops. Repeat until color changes, and stops changing.
5) The last drop that caused a change is the drop count. Multiply #drops by 10 [25] to get TA.

Calcium Hardness Test
Use quantities in [brackets] if CH is very high.

1) Rinse and fill sample tube to 25ml [10ml] mark.
2) Add 20 drops [10 drops] R-0010; swirl to mix.
3) Add 5 drops [3 drops] R-0011L; swirl 20-30 seconds to mix. Solution turns red to indicate calcium is present.
4) Add R-0012 one drop at a time, swirling continuously, 20-30 sec between drops. Repeat until color changes to blue (and stops changing).
5) The last drop that caused a change is the drop count. Multiply #drops by 10 [25] to get CH.

 

[PaulR]

TA 100 (using 10ml sample dilution method)
CH 350 (using 10ml sample dilution method)

It's not really correct to call it a "dilution method" if you say "dilution" then we think you're diluting the pool-water sample. You're just using a 10ml sample.

Your TA is not high enough to warrant using a 10ml sample. (I don't know that I've ever seen a TA report that was high enough to warrant that, I may remove it from the instructions.) Using a 10ml sample for CH is a time/accuracy tradeoff, as following the instructions exactly with a 25ml sample and 300+ CH means it takes 10+ minutes to run the test.

I added enough 6% bleach to raise FC to 8.5. Everything else is within range except for CYA. But overall numbers look good? Do I keep pH within normal recommended range now (instead of below normal)?

As far south as you are, some people run with CYA 60 on purpose. Hopefully you will get rain over the winter and that will help dilute it a bit more over time.

My concern about pH was because a combination of high pH, CH, and TA can lead to calcium scaling. With your current CH and TA this is not really a concern, so you can use the normal pH range.
--paulr

 

[polyvue]

Determine how much chlorine and muriatic acid you add on a daily basis. Try to anticipate both acid and chlorine demand for that week; right before you leave, adjust the pH and chlorine with enough of the chemicals to make adjustment unnecessary for 7 days.

What if the amount need to be added will put pH way low for the first few days after addition? FC way high is a plus! semi shock.

Not really sure what type of shock* this is... dichlor? If the powdered shock makes the pool a bit acidic, then you can compensate for that by putting in less muriatic acid than you normally would. Kind of works out nicely. The only thing I would want to emphasize is that if you become accustomed to exercising the convenience of powdered shock you'll end up with a very high level of CYA once again; an undesirable situation I'm sure you'll agree!

I knew what you meant when you spoke of diluted samples, so ignored it, but I agree with Paul that there's no compelling reason to use a 10 mL sample for Total Alkalinity that is in the 90-150 ppm range. (However, if you elect to do this in the future the world will not come to an end. I use a 10 ml sample for the Calcium Hardness test, for the same reason you elucidated... I think most folks here don't test very often for CH and therefore don't worry about using 20 drops of solution per test.)

EDIT * After reading this again, I'm not sure I caught the correct syntax... and could have misunderstood. If you're just voicing concern about the pH swing intrinsic to applying a 7-day dose of muriatic acid I wouldnt worry too much. The pH has a tendency to rise, correct? So a few days hovering in the high 6s or low 7s isn't going to hurt anything. Presume that you'll be programming a daily filter/pump cycle. END EDIT

 

[PaulR]

2nd questions is: going away for vacation for one wk. Any recommendations?

Missed this first time around.... there are various tactics. One is to bring pH down to the low end (7.0-7.2) and dump in a pile of bleach. With CYA 60 this is a pretty reasonable approach. Works even better if you have a cover.

Another approach is to bring FC up just a few points with bleach, and a few tabs of trichlor in a floater. The extra CYA this will add is minimal; I find 3 tabs do well for a 1-week trip. Also if you use trichlor you probably don't have to bother with the acid, because the trichlor itself is pretty acidic.

Most important.... remember what you did before you left, see how things stand when you get back, and use that to help you figure out what to do next time.
--paulr

 

[irvinenewbie]

Thanks for the advice, everyone.

EDIT * After reading this again, I'm not sure I caught the correct syntax... and could have misunderstood. If you're just voicing concern about the pH swing intrinsic to applying a 7-day dose of muriatic acid I wouldnt worry too much. The pH has a tendency to rise, correct? So a few days hovering in the high 6s or low 7s isn't going to hurt anything. Presume that you'll be programming a daily filter/pump cycle. END EDIT

that's exactly what I meant. I guess I need to improve my communications skills. I was just kidding about shock. Nothing will be added besides bleach. FC will just be really high, almost approaching shock level - i.e. semi shock.

Most important.... remember what you did before you left, see how things stand when you get back, and use that to help you figure out what to do next time.

Will do. will report when I come back. Thanks.