New Plaster Worries

[annifred]

Hi,

I have just finished a pool renovation - new pebble plaster, tile and coping. The plaster was applied 6 days ago, acid washed 5 days ago and finished filling 3 days ago. Chemistry of the water when filling was complete was Cl - zero, pH 7.2, CH 400, alkalinity 150.

Equipment start up was yesterday (finished filling on Friday and first available start-up technician was Tuesday.

I have brushed the pool twice and the water looks mostly clear and nice. However, the chemistry seems nuts and I can’t find any refs to what might cause alkalinity to be >500, CH about 900, pH 7.2, Cl 4

I haven’t added a sequestering agent yet, the start up procedure said it was optional (but recommended) so based on the tests I did on day one I thought I would wait and see.

 

[ajw22]

TA of 500 and CH of 900 sounds like testing errors. Retest and walk us through what ML sample and how many drops it took.

Post a complete set of test results. FC?

Review...

Calcium Hardness

A drop-based test that measures the hardness in your water. Once measured, it is used … Read more…

www.troublefreepool.com

Total Alkalinity

A drop-based test used to measure the alkalinity in water. Alkalinity helps serve as a … Read more…

www.troublefreepool.com

and read the notes:

• Sometimes a static electric charge can build up on the R-0009 dropper bottle tip, causing the drops to be smaller than usual and making the test read higher than actual. You can prevent this by wipping the tip of the dropper bottle with a damp cloth or tissue before you start and after each drop.
• Hold the dropper bottles vertically and squeeze gently, so that drops come out slowly and seem to hang on the tip of the dropper bottle for a moment before falling.
• If you expect that your TA level is extremely high, you can do the test so that each drop is 25, instead of 10, to speed up the process and save on reagent usage. Use 10 ml of pool water, 1 drop of R-0007, 3 drops of R-0008, and multiply the number of drops of R-0009 by 25 to get your TA level.
• R-0007 is thiosulfate, used to neutralize chlorine so it won’t interfere with the test. Extra R-0007 can be added when the FC level is very high to help prevent the dye from bleaching out.

This may also help you..

Plaster Start-Up Guides - Further Reading

www.troublefreepool.com

 

[RMcGirr83]

What are your using to test with? I'm skeptical if your TA is really higher than 500. That's nutz

 

[annifred]

TA of 500 and CH of 900 sounds like testing errors. Retest and walk us through what ML sample and how many drops it took.

Post a complete set of test results. FC?

Review...

Calcium Hardness

A drop-based test that measures the hardness in your water. Once measured, it is used … Read more…

www.troublefreepool.com

Total Alkalinity

A drop-based test used to measure the alkalinity in water. Alkalinity helps serve as a … Read more…

www.troublefreepool.com

and read the notes:

• Sometimes a static electric charge can build up on the R-0009 dropper bottle tip, causing the drops to be smaller than usual and making the test read higher than actual. You can prevent this by wipping the tip of the dropper bottle with a damp cloth or tissue before you start and after each drop.
• Hold the dropper bottles vertically and squeeze gently, so that drops come out slowly and seem to hang on the tip of the dropper bottle for a moment before falling.
• If you expect that your TA level is extremely high, you can do the test so that each drop is 25, instead of 10, to speed up the process and save on reagent usage. Use 10 ml of pool water, 1 drop of R-0007, 3 drops of R-0008, and multiply the number of drops of R-0009 by 25 to get your TA level.
• R-0007 is thiosulfate, used to neutralize chlorine so it won’t interfere with the test. Extra R-0007 can be added when the FC level is very high to help prevent the dye from bleaching out.

This may also help you..

Plaster Start-Up Guides - Further Reading

www.troublefreepool.com

Thanks Allen - I redid all the tests on two different fresh samples. I’m using my TFTest kit and directions.

The TA on a 10mL sample as you suggested is 200 (I did wipe the tip of the R-0009 reagent which I confess I normally don’t bother to do), FC is 4.5 (apologies, I labeled that result “Cl” in my original post), CH is 400 and pH is still 7.2

So not so alarming or puzzling as my first results. Maybe I erred somewhere or introduced a contaminant somehow. I should have resampled and retested before I panicked, lesson learned.

Thank you for the link to the TFP plaster start up guide, I did not find that when I first looked for answers on the blog. I will also review the other links for CH and TA.

Thanks for your help.
Anne

 

[annifred]

What are your using to test with? I'm skeptical if your TA is really higher than 500. That's nutz

Agreed - not sure what the heck I did. I’m using TFTest kit, reagents are fresh and I’ve done all the tests a zillion times before so either I crossed some mental wire that hasn’t been crossed before or my sample got contaminated in some peculiar manner.

Resampled & retested with more conventional results. TA still seems high at 200, not sure if this is expected. I’m following the contractor’s directions to use the NPC start up procedure. The only uncertainty is it says add no chlorine for 48 hours - I took that to mean 48 hrs after filling the pool, and since we started the filter up 3 days after the pool was filled I did add chlorine on day one of running the filter.

I see that the TFP new plaster guide says don’t add chlorine until after no more plaster dust is evident, so I hope that adding chlorine while it was still a bit cloudy isn’t catastrophically bad. It is also a bit higher than their recommended 1.5 - 3ppm

 

[ajw22]

Resampled & retested with more conventional results. TA still seems high at 200, not sure if this is expected.

Your TA only matters for how your pH rises or falls. With a pH of 7.2 your TA is fine. You will find your pH will rise and you will need to add muriatic acid every few days to keep pH below 8. That is normal with new plaster and a TA that high. In time adding acid will lower your TA. Although with a TA of 150 on your fill water you will always be batteling high TA and rising pH.

I’m following the contractor’s directions to use the NPC start up procedure. The only uncertainty is it says add no chlorine for 48 hours - I took that to mean 48 hrs after filling the pool, and since we started the filter up 3 days after the pool was filled I did add chlorine on day one of running the filter.

That's fine. No chlorine for 48 hours after water is in the pool to let the plaster cure.

I see that the TFP new plaster guide says don’t add chlorine until after no more plaster dust is evident, so I hope that adding chlorine while it was still a bit cloudy isn’t catastrophically bad. It is also a bit higher than their recommended 1.5 - 3ppm

That's fine. Try and keep your FC at 3ppm or below to not bleach your new plaster. Usually we say being high on FC is not a problem but with new plaster don;t over do it.

 

[annifred]

Your TA only matters for how your pH rises or falls. With a pH of 7.2 your TA is fine. You will find your pH will rise and you will need to add muriatic acid every few days to keep pH below 8. That is normal with new plaster and a TA that high. In time adding acid will lower your TA. Although with a TA of 150 on your fill water you will always be batteling high TA and rising pH.



That's fine. No chlorine for 48 hours after water is in the pool to let the plaster cure.



That's fine. Try and keep your FC at 3ppm or below to not bleach your new plaster. Usually we say being high on FC is not a problem but with new plaster don;t over do it.

Great, thanks again for your help