Pool Math questions

[geh]

First off, I paid for a premium subscription for the Pool Math app. Then I logged into the app with my TFP forum credentials. Now it says to subscribe for unlimited test logs. I am assuming the one premium subscription will be good for all my devices? How do I sync them so I have the premium subscription linked to my TFP account, and on multiple devices?

Now, I used my Taylor K-2006 for the first time today and this is what I came up with:

FC 7.8
CC .04
PH 7.5
TA 140
CH 360
CYA 84
Borate 20 (from test strip)

Pool Math is recommending a significantly higher chlorine level due to the high CYA, and my borate is very low. So I am thinking the first things I should do is lower the CYA significantly through partial draining and refilling, then bring the borate level up and balance the expected Ph swing, then re-test the water and get alkalitinity in line, then balance the chlorine. Does that sound like a good plan? Also I think my water is already hard but within ok range, but Pool Math is telling me to add calcium chloride to make it harder, if I am not mistaken. Not sure if I should do that.

FYI, from a water test from the pool store two days ago (I had almost zero chlorine at the time) it showed:

hardness 231
TA (w/stabilizer correction) 86
CYA 87
copper .1 ppm
iron .2 ppm
borate 15 ppm

My pool is plaster/chlorine 11.7x40 ft avg. depth 4.5 and calculated 15,600 gallons. Also here is a read only link to a google spreadsheet I started today with test results: Pool Maintenance Murlesan


Thanks in advance for the guidance.

 

[geh]

Update on the subscription: the log I entered on the Pool Math app on my iPhone did share with the app on my iPad, but I still get the subscription upgrade message. App Store confirms I paid for the subscription

 

[ajw22]

How do you chlorinate your pool?

@Leebo should be by soon to assist with the subscription problem.

 

[geh]

I just switched from Clorox Xtra Blue shock and tablets, to 12% bleach from the pool store. Its cheaper than Clorox bleach at the hardware store. I'm paying $4.50/gal for the 12%. So the previous Clorox pool products would explain the high CYA and the copper.

 

[ajw22]

Now, I used my Taylor K-2006 for the first time today and this is what I came up with:

FC 7.8
CC .04
PH 7.5
TA 140
CH 360
CYA 84
Borate 20 (from test strip)

Pool Math is recommending a significantly higher chlorine level due to the high CYA, and my borate is very low. So I am thinking the first things I should do is lower the CYA significantly through partial draining and refilling, then bring the borate level up and balance the expected Ph swing, then re-test the water and get alkalitinity in line, then balance the chlorine. Does that sound like a good plan? Also I think my water is already hard but within ok range, but Pool Math is telling me to add calcium chloride to make it harder, if I am not mistaken. Not sure if I should do that.

First thing you need to drain or do a water exchange to bring your CYA down to 30-40 ppm. BTW, your CYA is 90. When the dot disappears between 90 and 80 we round up and call it 90. The lines are logarithmic, not linear and you can't eyeball values between the lines.

Draining - Further Reading

www.troublefreepool.com

Once you get the water to CYA 30-40 then raise the FC with liquid chlorine to 5-7 ppm following the PoolMath.

What is the pH, TA & CH of your fill water?

You need to lower your TA before you add borates. I would let your pool water pH and TA settle for a at least a few weeks before adding borates. TA and borates are the least important chemicals to adjust.

Lower Total Alkalinity

A lower Total Alkalinity level can help a pool owner stabalize their pH increase. We'll explain how to lower TA with a little help from muriatic acid.

www.troublefreepool.com

 

[geh]

Thank you. That is what I was thinking is the first thing to do is bring down the CYA and everything else should be adjusted accordingly off of that new level. I'll follow what you suggested in that order. Not sure about the levels in municipal water that I will be using to fill. I guess I should test the pool water after it is refilled and go from there? Regarding the TA, there are two sets of numbers: the first is my first use of the Taylor k-2006 kit, the second st of numbers is water tested by the local pool store two days earlier, where they use the centrifuge type device. Theirs said 86, mine said 140, so there is a good possibility my number is off since it was my first time testing. As I recall, the TA involved a light blue color and as I was holding it to the sky it looked clear but after I added more drops I used indirect sunlight and could see the blue tint a lot better. I'm guessing thier TA number is probably a better one to go off of than mine. Granted I added muriatic acid and bleach after that test and before my own test, but if I understand it correctly that should not affect the alkalinity. Thanks again/Gerald

 

[geh]

I may have some questions about turning off my skimmers and draining the pool level well below that, but instead of waiting for that, any guidance to drain about 1/3 of the pool? I think I need to start turning valves to see which ones turn off the skimmers, but beyond that should the pool then drain from the two drains in the bottom of the deep end? Also, is waste a faster way to drain than backwash and rinse?

 

[ajw22]

We ignore pool store tests as we find them unreliable. Trust your own testing.

Your TA can change based on your fill water TA. So your current TA is irrelevant and why I asked about your will water pH and TA. That tells us what you are likely to end up with.

 

[DanF]

It's not urgent to test your fill water, but you should soon because it is good info for determining how evaporation will impact your chemistry.

Also, when draining your pool in order to lower CYA, don't drain much before you start to refill. In New Orleans the water table is pretty high and you dont want to risk floating your pool.

 

[ajw22]

I may have some questions about turning off my skimmers and draining the pool level well below that, but instead of waiting for that, any guidance to drain about 1/3 of the pool? I think I need to start turning valves to see which ones turn off the skimmers, but beyond that should the pool then drain from the two drains in the bottom of the deep end? Also, is waste a faster way to drain than backwash and rinse?

Do not use your pool pump to drain. You risk damaging an expensive pool pump.

Read Draining - Further Reading

 

[ajw22]

Also, when draining your pool in order to lower CYA, don't drain much before you start to refill. In New Orleans the water table is pretty high and you dont want to risk floating your pool.

That is why we have the No Drain Water Exchange Process

 

[jseyfert3]

Welcome to TFP!

Sorry in advance for my post length, I noted a couple things I wanted to comment on, I'm on my computer instead of my phone and I'm not in a hurry to do other things. This combination means my post length is 3x what it probably should be.

I am assuming the one premium subscription will be good for all my devices? How do I sync them so I have the premium subscription linked to my TFP account, and on multiple devices?

If you haven't already, try going to About TFP in the app menu and clicking Restore Subscription. If that doesn't work once Leebo gets here he'll get you figured out. You can have it on more than one device, I had it on two Android devices then upgraded my phone and switched to an iPhone, so it's actually on three devices currently. I know I've had to use that Restore Subscription button at least once.

Now, I used my Taylor K-2006 for the first time today and this is what I came up with:

FC 7.8
CC .04

You can do the FC/CC test two different ways. You can use a 25 mL sample and each drop is 0.2 ppm, or a 10 mL sample and each drop is 0.5 ppm. We recommend you use the 10 mL sample, the extra resolution of the 25 mL sample is usually unnecessary and the FC levels TFP recommends means a lot of extra reagent is used for no reason when doing a 25 mL sample vs 10 mL sample. Plus it's a lot less drops, which makes the test quicker and easier.

TA 140
CH 360

For TA and CH, you also have a choice of two different sample sizes. For both, a 10 mL sample size means the last reagent added is 25 ppm per drop, and a 25 mL sample means 10 ppm per drop. Generally you switch between sample sizes based on anticipated levels, switching between the two somewhere around 100 ppm. In this case, using 10 mL instead of 25 mL your test result would likely be TA of 150 and CH of 350, except instead of the 14 and 36 drops you used for the final step it would be only 6 and 14 drops, respectively.

Also keep in mind these different sample sizes have no hard and fast rules, and you can use either as desired, but if you don't need the 10 ppm resolution for levels of around 100 and below you can save reagent and test time by using the smaller sample size.

When using the smaller sample size, refer to the "When high TA/CH is anticipated" portion of the test kit instructions, as the number of drops in the first part of each test also change.

Also I think my water is already hard but within ok range, but Pool Math is telling me to add calcium chloride to make it harder, if I am not mistaken. Not sure if I should do that.

For a CH of 360 I don't think it should be recommending that. I typed your values into my "test" pool on my own PoolMath app and it says it's within ideal values. Can you post a screenshot and/or explain why you think it's telling you to add calcium?

Not sure about the levels in municipal water that I will be using to fill. I guess I should test the pool water after it is refilled and go from there?

To find the levels, take a sample of your tap water and test it for TA and CH. Other tests on tap water are not needed (unless you're curious). If your home has a water softener, be sure to take a sample that is from an unsoftened tap, unless the pool is filled from a softened tap. (A properly working water softener reduces the CH to almost zero. Fun fact: You can use your CH test to check proper functioning of a water softener)

As I recall, the TA involved a light blue color and as I was holding it to the sky it looked clear but after I added more drops I used indirect sunlight and could see the blue tint a lot better.

TA test is green to red. CH test is red to blue. Note it's not clear in the Taylor instructions but you should not stop at the first hint of color but continue until last drop doesn't change the color, then don't count that last drop. For example, on the TA test I usually will see the green fade away mostly with some red, the next drop will make it a bright red and the following drop doesn't increase the color further. That last drop is not counted, but the one that made it a bright red is counted.

If you don't have, I personally recommend a SpeedStir. Not only does it rapidly stir the sample during the test, eliminating the need to swirl and speeding up the test time, but it also has lights that light up the sample which greatly helps in watching the color change of the tests.

 

[geh]

Thanks for the great replies. I just got home at 2 AM after a long work assignment, but plan to read up more thoroughly tomorrow evening when I have some idle time. Great info and greatly appreciated
/Gerald

 

[geh]

It's not urgent to test your fill water, but you should soon because it is good info for determining how evaporation will impact your chemistry.

Also, when draining your pool in order to lower CYA, don't drain much before you start to refill. In New Orleans the water table is pretty high and you dont want to risk floating your pool.

Yes the water table is high here. I believe when they re-plastered my pool earlier this year they open the drains at the bottom to alleviate pressure and allowed some ground water to come up. Not sure what they did to remove that dirty water to plaster that part but likely involved a sump pump or something. I only plan to drain about a third of the pool.