New Pool Chemistry Questions

[JohnnyRBravo]

Hi All,

I've got a new pool and have been through all the basic chemistry instructions, read the pool school ebook and recommended articles. I also bought a Taylor test kit and have been adjusting the pool water for about a month. It's pretty close to the recommended levels.

A couple of questions about testing:
1) The test kit talks about the need to test within a minute of sampling from the pool. They claim that time can influence the test results. However, given the number of tests and the time it takes to conduct each, this seems unattainable. Comments?

2) The test kit also talks about the need to get the exact amount of pool water for each test (down to the drop!). I can see that the wrong amount of water would affect the test, but to the drop! Really? How sensitive are these tests to a drop's difference in the pool water?

3) As I have reduced the pH over the last couple of weeks (using muriatic acid), the TA has gone down (obviously, since lower pH is more acidic). Is there a way to increase the TA without increasing the pH?

One additional question, not directly about testing but related:

4) I've spent some time estimating the pool volume. Since it's an irregular shape with varying depths, I've broken it down into four circles and calculated the volume based on that. There's still an area (of varying depth) that's not covered by the circles, so I'm still working on a better estimation. My volume turns out to be approximately 11.6K, so I've scaled the lookup tables provided in the kit. I interpolated the values between 10K and 15K using linear scaling. I hope that is an appropriate scaling. Comments?

 

[YippeeSkippy]

To answer-
1) I'd say within the minute is a stretch.... who could do it?! It is safe to say get your sample and perform the tests soon, but hardly will it change if it is 10 minutes later! Some folks like to let cold water warm up in the house for the CYA test in fact. You just don't want to grab a container and let it sit out, exposed to the sun or something for an hour or two..y'know?

2) Test tube vials have such small writing, and the space between levels is tight. I'm good at eyeballing it and knowing to read it at the meniscus (the bottom of the curve in the water) which is the proper level. But if you are unsure of yourself you can always get a syringe or this device which makes the same accurate :
Sample Sizer Measuring Tool

3) Baking soda will raise TA with only a small tap up of pH.

4) As you add chemicals based on PoolMath, you may find that the expected response is more or less than predicted. If you monitor this you may be able to determine how far off your pool volume is from what you assumed. Pay attention to the bottom of PoolMath where is tells you the effect of adding x chemical and what you should expect. If it is more than you can surmise your pool is a bit smaller than you thought. And if less, the pool is larger.

Maddie

 

[ajw22]

What test kit do you have?

 

[AUSpool]

Always go for your FC and CC as soon as practical as these are the two that will change the most in the shortest amount of time.

Out of interest what are your current levels and in particular your TA? Most of us running a SWG find a low TA ~60ppm helps to slow a rising pH.

 

[JohnnyRBravo]

Thanks for the responses. Here are answers to the questions asked:
1) Test Kit; Taylor Service Complete Pool Water Test Kit K-2006C
2) Current levels (after adding water to pool; adjustments noted): FC 0 (treated with 32 oz liquid chlorine); CC 0; pH 8+ (treated with 56 oz muriatic acid); TA 110; CH 370; CYA 50-60)

I don't have an SWG, just chlorine and Ozone/UV.

On another topic, someone mentioned PoolMath. I have the app, but one of the primary requirements is knowing pH. However, using the Taylor test kit, I'm only able to know how many drops of reagent it takes to drop the pH to 7.4. It doesn't let me know the actual pH. Can I calculate the actual from the drops of reagent?

 

[mknauss]

You measure pH by color matching with the guide next to the vial.

Do realize that the UV and ozone are not sanitation processes. You will need to add liquid chlorine EACH DAY during the spring/summer/fall months.

 

[JohnnyRBravo]

One other issue: when I use my Taylor test kit, I sometimes get a reading of FC=0, even after double the amount of reagent. I find this hard to believe; even my tap water turns the reagent "red".

 

[mknauss]

Also - your TA is currently quite high. Do not add anything to raise it. Just manage your pH in the 7's and the TA will drop to a normal level.

 

[mknauss]

Then you have 0 FC. You need to add liquid chlorine. See FC/CYA chart

 

[ajw22]

On another topic, someone mentioned PoolMath. I have the app, but one of the primary requirements is knowing pH. However, using the Taylor test kit, I'm only able to know how many drops of reagent it takes to drop the pH to 7.4. It doesn't let me know the actual pH. Can I calculate the actual from the drops of reagent?

Don’t you have the pH test 9058 comparator? Add 5 drops and match the closest color to determine your pH.

Taylor 2000 Series Comparator # 9058

• ajw22
• Feb 9, 2019

Taylor 2000 Series Comparator # 9058

 

[ajw22]

One other issue: when I use my Taylor test kit, I sometimes get a reading of FC=0, even after double the amount of reagent. I find this hard to believe; even my tap water turns the reagent "red".

Tap water contains around 1.5 ppm of chlorine added by your municipal water supplier.

 

[JohnnyRBravo]

@ajw22, Yes, I have the color comparator that comes with the Taylor Test Kit. When I add the 5 drops, the color is much, much, more red/purple than the highest reading (8.0). It can take up to 15 drops of the reagent to get it to one of the colors on the comparator. So after that, I know how much muriatic acid to add to bring it down, but not what the actual pH is. Perhaps, there's a formula for converting the reagent drops into pH levels but I don't know what it is...

 

[ajw22]

@ajw22, Yes, I have the color comparator that comes with the Taylor Test Kit. When I add the 5 drops, the color is much, much, more red/purple than the highest reading (8.0). It can take up to 15 drops of the reagent to get it to one of the colors on the comparator. So after that, I know how much muriatic acid to add to bring it down, but not what the actual pH is. Perhaps, there's a formula for converting the reagent drops into pH levels but I don't know what it is...

That test only measures up to pH of 8. The color you get says pH is greater then 8. To use PoolMath in that situation enter 8.2 as pH and add the amount of MA PM says. Retest in 30 minutes and repeat until you get a pH reading below 8.

Are you retesting your pH 30 minutes after you add the MA you figure is required?

You should check your pH more often and not let it get so high.

 

[JohnnyRBravo]

@mknauss, thanks for your multiple comments. Yes, I know about reading the pH from the color comparator. However, as noted in my reply to @ajw22, the scale only goes to 8.0 and it can take me up to 15 drops to get it back to a matching color. I also understand that UV and ozone aren't for sanitation and I do use liquid chlorine [having switched from TSSA tablets, due to a CYA buildup]. In a related topic, I have read recently that UV and ozone provide oxidation, thereby reducing the oxidation demands on the chlorine (Ozone and UV systems allow pool owners to approach no-chlorine systems - AQUA Magazine). Finally, my TA has indeed some down to an acceptable level although the CYA is on the high side.

Latest numbers, prior to treatment: FC: 0.2, CC:1, pH: 8+, TA: 100, CH:370, CYA: 60

 

[JohnnyRBravo]

@ajw22, thanks for your comments. As to the retesting: I have been waiting for several hours to allow the pump to mix the MA thoroughly. I wasn't aware that I should test again that soon. I'll try that, as well as your PoolMath strategy.

 

[ajw22]

In a related topic, I have read recently that UV and ozone provide oxidation, thereby reducing the oxidation demands on the chlorine (Ozone and UV systems allow pool owners to approach no-chlorine systems - AQUA Magazine).

UV & ozone are a waste of money for an outdoor pool. You get all the free UV you need from the sun.

TFPs view is - Alternative sanitizers and "chemical free" pools--The Truth!

 

[ajw22]

@ajw22, thanks for your comments. As to the retesting: I have been waiting for several hours to allow the pump to mix the MA thoroughly. I wasn't aware that I should test again that soon. I'll try that, as well as your PoolMath strategy.

In several hours your pH will have risen. You want to see what the effect is of your MA.

Your FC is WAY too low. It should never get that low.

I suggest you review ABCs of Pool Water Chemistry

 

[AUSpool]

@ajw22, Yes, I have the color comparator that comes with the Taylor Test Kit. When I add the 5 drops, the color is much, much, more red/purple than the highest reading (8.0). It can take up to 15 drops of the reagent to get it to one of the colors on the comparator. So after that, I know how much muriatic acid to add to bring it down, but not what the actual pH is. Perhaps, there's a formula for converting the reagent drops into pH levels but I don't know what it is...

You really have been up speced in the equipment department. I was confused with your ‘inline chlorinator’, I suspect its a tablet feeder if its not a SWC.

If your pH / indicator sample is more purple than red you may have halogen interference. Try adding a drop of R0007 to a sample before the pH indicator.

 

[YippeeSkippy]

I just want to confirm that your comparitor block is the one with the large round tube section for pH, not the smaller square tube? Both are from Taylor and they use different reagents (both phenol red though) so this might explain the confusion??
Or this smaller one from the Basic Taylor K-1000 kit==>
HDX/PoolMaster Kits to Test PH - Not a good idea

 

[JohnnyRBravo]

You really have been up speced in the equipment department. I was confused with your ‘inline chlorinator’, I suspect its a tablet feeder if its not a SWC.

If your pH / indicator sample is more purple than red you may have halogen interference. Try adding a drop of R0007 to a sample before the pH indicator.

Steve, thanks for the comments. Yes, the "Inline Chlorinator" (their name, not mine] is a tablet feeder. I'm no longer using it after reading the benefits of liquid chlorine versus tablets.

I'm not sure what "halogen interference" is? Could you expand on the condition? I'm happy to try it!