correcting high TA?

[M Ryan]

New vinyl pool owner. Located in the Southeast. Just experienced a long period of rain.

Using Borax, Bleach, Chlorine Tabs, Washing Soda

noticed pH was on the low end (around 6.8) and I added arm and hammer washing soda using the pool math calculator to raise it around 7.4. Afterwards the water became cloudy & dull. When brushing there’s a haze of “dust” that comes off the bottom and sides. Calcium deposits? Algae starting?

Acquired a Taylor TF-100 kit and obtained some values for your consideration:

Cl/Br- 5-10
pH-7.4
FC-4 ppm
CC-0 ppm
TC-4 ppm
Calcium Hardness-75 ppm
TA-180
CYA- 100<

What should my plan of attack be? I’ve read muriatic acid to lower the TA but unsure what the brown haze could be. Calcium deposits? Thanks for your help!

 

[Rocket J Squirrel]

What does "CYA- 100<" mean? If your CYA is anywhere near 100, you need to lower it by draining half your water & refilling (hopefully with rain water). Your FC is way too low for high CYA and the "dust" is probably algae.

PS: Welcome to TFP! Please have a look at Pool Care Basics.

 

[HermanTX]

Welcome to TFP.
Suggest you stop using chlorine tabs as that is adding CYA to your pool. It appears it is too high already so don’t continue to add tabs. Only use liquid chlorine to manage your FC.
For future test results
No need to report CL/Br as that is just a quick test to determine if Chlorine is present.
It is best to use the powder and drops to report FC and CC - also no need to report TC as you can see that is the sum of FC & CC
MA does lower TA but it also lowers pH - you have to be mindful of that. For your 20k gal pool a quart of MA (31.4%) will lower pH by 0.2 and TA by 3.1. So it will take time to reduce your TA significantly. Basically, you have add MA, then let pH creep up to 7.9 or so then add more MA to reduce both. It may take many cycles to reduce your TA.

Have you tested the tap water that fills your pool? It would be good to know the TA of that water so you know what is being added when you have evaporation.

As noted by @Rocket J Squirrel the high CYA is a concern and will require you to lower it to properly chlorinate your pool.

 

[M Ryan]

What does "CYA- 100<" mean? If your CYA is anywhere near 100, you need to lower it by draining half your water & refilling (hopefully with rain water). Your FC is way too low for high CYA and the "dust" is probably algae.

PS: Welcome to TFP! Please have a look at Pool Care Basics.

Thank you for your reply… I used the TF-100 CYA view tube and looked down the tube at waist level and filled the view tube slowly until I could no longer see the black dot in the bottom of the tube. This resulted in a reading greater than 100.

 

[M Ryan]

Welcome to TFP.
Suggest you stop using chlorine tabs as that is adding CYA to your pool. It appears it is too high already so don’t continue to add tabs. Only use liquid chlorine to manage your FC.
For future test results
No need to report CL/Br as that is just a quick test to determine if Chlorine is present.
It is best to use the powder and drops to report FC and CC - also no need to report TC as you can see that is the sum of FC & CC
MA does lower TA but it also lowers pH - you have to be mindful of that. For your 20k gal pool a quart of MA (31.4%) will lower pH by 0.2 and TA by 3.1. So it will take time to reduce your TA significantly. Basically, you have add MA, then let pH creep up to 7.9 or so then add more MA to reduce both. It may take many cycles to reduce your TA.

Have you tested the tap water that fills your pool? It would be good to know the TA of that water so you know what is being added when you have evaporation.

As noted by @Rocket J Squirrel the high CYA is a concern and will require you to lower it to properly chlorinate your pool.

Thank you… I will use liquid chlorine in the future.

So my first order of business should be addressing the high CYA by lowering the pool? Then shouldn’t I wait to address the TA until after refilling?

 

[M Ryan]

Thank you… I will use liquid chlorine in the future.

So my first order of business should be addressing the high CYA by lowering the pool? Then shouldn’t I wait to address the TA until after refilling?

I have not tested the tap water yet… that would be good information to have. Thank you

 

[HermanTX]

Thank you… I will use liquid chlorine in the future.

So my first order of business should be addressing the high CYA by lowering the pool? Then shouldn’t I wait to address the TA until after refilling?

Yes. Everything will change when you drain 50% or more of your pool. Doing the test on your tap water will help plan for what your new water will be. However prior to draining, suggest you do a dilution test on your CYA.

Take the CYA bottle and fill it half with pool water and the other half with tap water. Tap water has no CYA. Shake it up well, then pour half out such that the remainder is your “diluted pool sample”. Then fill the bottle with the R-0013 Reagent as per the test directions. Shake it well and let sit for 30 seconds. Then pour into the CYA tube to read the CYA value. Whatever is your value you need to multiple it x2. So if you now read 60ppm, then your real CYA is 120ppm. It is not perfect but provides a better value then being >100.

Also, you may want to try this method for reading your CYA as I find it easier and avoids staring at the dot as you pour.
Pour the mixed solution to a known level, say 90, peer in and confirm you can see black dot. Now pour mixed solution to 80 mark, peer in again, if you can still see dot, hold tube up and pour mixed solution to the 70 mark, then peer in again to view dot. Continue this until you are not able to see the dot - then use your CYA number as the value you last saw the dot. This method avoids constantly looking down the tube which can create the illusion of always seeing the dot due to staring down the tube. This also helps that you only report CYA values in decade numbers due to the logarithmic scale of the tube.

 

[pjt]

Using Borax, Bleach, Chlorine Tabs, Washing Soda

Of all those items, only the bleach is necessary. The tabs are contributing to your problems.

noticed pH was on the low end (around 6.8) and I added arm and hammer washing soda

Low pH likely due to tab use. Any idea what your TA was before adding the washing soda? Aeration will increase pH without affecting TA. High TA will cause the pH to drift up quickly.

When brushing there’s a haze of “dust” that comes off the bottom and sides.

Algae because your FC was too low for your CYA level.

TA-180
CYA- 100<

If your CYA is 100+, you'll want to drain and refill at least half your water. No point fixing the rest of your water chemistry until that's done.

 

[M Ryan]

Of all those items, only the bleach is necessary. The tabs are contributing to your problems.


Low pH likely due to tab use. Any idea what your TA was before adding the washing soda? Aeration will increase pH without affecting TA. High TA will cause the pH to drift up quickly.


Algae because your FC was too low for your CYA level.


If your CYA is 100+, you'll want to drain and refill at least half your water. No point fixing the rest of your water chemistry until that's done.

Thank you, makes perfect sense…

Sounds like a drain & refill is needed before any water chemistry issues can be addressed.

Should I simultaneously add water while draining as to not cause liner damage? I’m thinking about placing a submersible pump in the deep end and running the outlet into a storm drain (after checking with the city) while leaving a garden hose turned on in the skimmer basket. Should I aim to match the GPH output of the pump? Use more then one garden hose in the skimmer basket?

From there my guess would be to periodically check the CYA and stop once it reaches an acceptable value? What should I shoot for? A CYA of 40?

I will test the water supply from the garden hose but what chemicals should I have on hand immediately following the refill and should I expect to fight the algae afterwards?

Thank you! I would not know how to proceed without everyone’s help…

 

[M Ryan]

Yes. Everything will change when you drain 50% or more of your pool. Doing the test on your tap water will help plan for what your new water will be. However prior to draining, suggest you do a dilution test on your CYA.

Take the CYA bottle and fill it half with pool water and the other half with tap water. Tap water has no CYA. Shake it up well, then pour half out such that the remainder is your “diluted pool sample”. Then fill the bottle with the R-0013 Reagent as per the test directions. Shake it well and let sit for 30 seconds. Then pour into the CYA tube to read the CYA value. Whatever is your value you need to multiple it x2. So if you now read 60ppm, then your real CYA is 120ppm. It is not perfect but provides a better value then being >100.

Also, you may want to try this method for reading your CYA as I find it easier and avoids staring at the dot as you pour.
Pour the mixed solution to a known level, say 90, peer in and confirm you can see black dot. Now pour mixed solution to 80 mark, peer in again, if you can still see dot, hold tube up and pour mixed solution to the 70 mark, then peer in again to view dot. Continue this until you are not able to see the dot - then use your CYA number as the value you last saw the dot. This method avoids constantly looking down the tube which can create the illusion of always seeing the dot due to staring down the tube. This also helps that you only report CYA values in decade numbers due to the logarithmic scale of the tube.

Thank you for articulating that so well, makes perfect sense and I will implement this method of testing going forward!

 

[HermanTX]

Thank you, makes perfect sense…

Sounds like a drain & refill is needed before any water chemistry issues can be addressed.

Should I simultaneously add water while draining as to not cause liner damage? I’m thinking about placing a submersible pump in the deep end and running the outlet into a storm drain (after checking with the city) while leaving a garden hose turned on in the skimmer basket. Should I aim to match the GPH output of the pump? Use more then one garden hose in the skimmer basket?

From there my guess would be to periodically check the CYA and stop once it reaches an acceptable value? What should I shoot for? A CYA of 40?

I will test the water supply from the garden hose but what chemicals should I have on hand immediately following the refill and should I expect to fight the algae afterwards?

Thank you! I would not know how to proceed without everyone’s help…

Draining - Further Reading

www.troublefreepool.com

 

[pjt]

I will test the water supply from the garden hose

Good plan.

what chemicals should I have on hand immediately following the refill

Liquid chlorine (several gallons) and muriatic acid.

What should I shoot for? A CYA of 40?

I would target a CYA of 40 or 50.

should I expect to fight the algae afterwards?

Yes. You'll follow the SLAM process to eliminate all the algae: SLAM - Shock Level and Maintain

Once you pass the SLAM exit criteria, you transition to routine operation by maintaining your FC at or above the target for your CYA level: Chlorine / CYA Chart

For long-term chlorination, you'll use LC or a SWG.

 

[M Ryan]

Draining - Further Reading

www.troublefreepool.com

very good info. I picked up a submersible pump this morning but my question is how much water is safe to drain off at a time considering I don’t want the vinyl liner to move?

I’ve read a few different things. 1/3 at a time, 1/2, and even down to 18 inches is okay in the shallow end. I just don’t want to cause any further damage…. Thank you!

 

[reggiehammond]

If you do the no drain exchange, you don't need to worry about the level changing at all. Just measure the submersible pump flow rate using a timer and a 5 gallon bucket. Then try to match the water hose intensity to the same rate using a timer and bucket, as well.