Questions about NPC pool plaster start up instructions

[FLDude]

Hi All,

Im getting my pool replastered this week and the company wanted to charge me $800 for starting up the pool so i decided to do it myself.

They gave me these instructions from the national plaster council and i have a couple of questions that i hope you can help me answer.

NPC plaster start up instructions:
National Plasters Council Procedure | NPT Pool Finishes | NPTpool.com/
The actual pdf is what they told me to use which can be found in that article.

Question 1

In the first steps on each day when testing the alkalinity it mentions total alkalinity but with a caveat:

"High alkalinity should be adjusted to 80ppm using prediluted muriatic acid*
*Total alkalinity - 1/3 cyanuric acid = corrected or carbonate alkalinity (field rate)"

Should i be going off of total alkalinity at this point or carbonate alkalinity? Its confusing because they put the caveat there but then specifically mention carbonate alkinity in the later instructions:

"4th - 28th day test ph, carbonate alkalinity and calcium hardness and repeat first day steps 1-5."

So im confused on whether i should be using both types of alkalinity or just one?

Question 2

The instructions mention to adjust calcium hardness on the second day, not the first. Is this correct? From all the research ive done people say to adjust calcium hardness immediately because it can cause damage to the plaster if you dont. Should i ignore their instructions and do it on the first day or stick to the second day?

Question 3

It says to adjust calcium hardness from day 4 - 28 slowly up to 200ppm.
Should i work out the difference needed, amount i need to add then add that a bit at a time each day to get to 200ppm over 24 days? Or once a week, every two weeks? etc

Question 4

Step 4 says that ph should be reduced to 7.2 - 7.6 adding pre-diluted muriatic acid if the alkalinity is already 80-100ppm. Im confused by this, if my ph is at 8 for example and my alkalinity is already at 80-100ppm wont adding muriatic acid lower the alkalinity below 80-100ppm? If my ph is 8 and alkalinity isnt 80-100ppm should i do something else other than add muriatic acid to get the ph down? The wording in this step has me very confused.

Thats it for now, i appreciate any and all advice.

Thanks!

 

[jesse-99]

I just had my pool replastered last month. I personally didn't pay attention to carbonate alkalinity, only TA. (but that's just me)

I waited a couple days to bring up my CH, mostly because I didn't have sodium chloride. What was your FILL water CH?

I didn't wait 28 days myself, I think within a week I had my CH up around 200, and within 2-3 weeks I had my CH around 250.

Adding MA is the only thing you need to do to bring pH down.... It's going to rise some with the new plaster, and if you have water feature. Just check it regularly, and drop to 7.4 or 7.2 as needed. I was checking pH every day for the first month. Every other day since (because my water features bring my pH up a LOT). Also be sure to check your TA (IMHO) each time you check pH, because you need to know your TA to properly adjust your pH.

My replaster job (Diamond Brite) is now 6-7 weeks old, and it's in perfect condition. WATCH YOUR CSI !!!

 

[JoyfulNoise]

Unless your CYA is very high, like over 100ppm, then the adjusted alkalinity and total alkalinity will be very close.

How are you chlorinating the pool and what have you added to chlorinate with? What is your current CYA level?

Waiting 24 hours to adjust CH is fine. You can't possibly do damage to your plaster in that time frame unless you do something royally stupid like pour in gallons of acid. Once the plaster is troweled and the aggregate is exposed, there is still some plaster cream left on the surface that will dissolve into your pool water and cause the CH to rise. Waiting 24 hours gives it time to do that. Again, the amount of calcium lost in that 24 hour waiting period really is insignificant.

ALWAYS, ALWAYS, ALWAYS adjust CH slowly and in small batches. Calcium chloride (CH increaser) can cause serious clouding of the pool if it is added too fast.

I wouldn't focus too much on holding EXACT values of TA. If your pH gets to 8, knock it down to 7.6 and then wait. Let the TA settle wherever it will. In these early days, the TA is going to remain elevated because of the fresh plaster. Just keep the pH in a good range and monitor the TA. If it falls significantly below 80ppm, then bump it up with small additions of baking soda.

 

[ajw22]

hat article.

Question 1

In the first steps on each day when testing the alkalinity it mentions total alkalinity but with a caveat:

"High alkalinity should be adjusted to 80ppm using prediluted muriatic acid*
*Total alkalinity - 1/3 cyanuric acid = corrected or carbonate alkalinity (field rate)"

Should i be going off of total alkalinity at this point or carbonate alkalinity? Its confusing because they put the caveat there but then specifically mention carbonate alkinity in the later instructions:

"4th - 28th day test ph, carbonate alkalinity and calcium hardness and repeat first day steps 1-5."

So im confused on whether i should be using both types of alkalinity or just one?

Your CYA should be a maximum of 30 so 1/3 of CYA is 10. So the difference between TA and Carbonate Alkalinity is 10. That is 1 drop of testing.

They ask your Carbonate alkalinity to be between 80 to 120 ppm.

So keep your TA between 90 and 120 and don't worry about the carbonate alkalinity adjustment. It really is not material and within your testing error for alkalinity.

Question 2

The instructions mention to adjust calcium hardness on the second day, not the first. Is this correct? From all the research ive done people say to adjust calcium hardness immediately because it can cause damage to the plaster if you dont. Should i ignore their instructions and do it on the first day or stick to the second day?

Wait for the second day to adjust your CH. You need to give the plaster time to cure.

The whole thing that PDF is driving you towards is on the second page where the targeted LSI is 0 to +0.3.

Our plaster expert, @onBalance , says...

It is actually necessary, to achieve a smooth and dense surface, to have about a +0.5 CSI during the first 30 days. This is because the plaster (cement paste) surface contains about 20% calcium hydroxide, which is somewhat soluble in balanced and slightly positive CSI water and can be dissolved away. The plaster surface needs to be "carbonated" before the CSI should be lowered to the acceptable and balanced range. And that generally is achieved during the first month under balanced water

CSI and LSI - Further Reading

www.troublefreepool.com

Question 3

It says to adjust calcium hardness from day 4 - 28 slowly up to 200ppm.
Should i work out the difference needed, amount i need to add then add that a bit at a time each day to get to 200ppm over 24 days? Or once a week, every two weeks? etc

The web page says:

Adjustments requiring more than 20 lb. of CaCl^2 should be pre-diluted and added in 10lb increments – morning and afternoon.

So do the adjustments in a maximum of 10lb increments.

Question 4

Step 4 says that ph should be reduced to 7.2 - 7.6 adding pre-diluted muriatic acid if the alkalinity is already 80-100ppm. Im confused by this, if my ph is at 8 for example and my alkalinity is already at 80-100ppm wont adding muriatic acid lower the alkalinity below 80-100ppm? If my ph is 8 and alkalinity isnt 80-100ppm should i do something else other than add muriatic acid to get the ph down? The wording in this step has me very confused.

Reduce your pH in increments of 0.2-0.3 and it will not effect your TA much.

Don't reduce your pH below 7.6.

 

[onBalance]

Please test your tap water (or fill water that will be filling the pool) and let us know what the alkalinity, calcium hardness, and pH is, and we will be able to provide better guidance for you.

 

[FLDude]

I just had my pool replastered last month. I personally didn't pay attention to carbonate alkalinity, only TA. (but that's just me)

I waited a couple days to bring up my CH, mostly because I didn't have sodium chloride. What was your FILL water CH?

I didn't wait 28 days myself, I think within a week I had my CH up around 200, and within 2-3 weeks I had my CH around 250.

Adding MA is the only thing you need to do to bring pH down.... It's going to rise some with the new plaster, and if you have water feature. Just check it regularly, and drop to 7.4 or 7.2 as needed. I was checking pH every day for the first month. Every other day since (because my water features bring my pH up a LOT). Also be sure to check your TA (IMHO) each time you check pH, because you need to know your TA to properly adjust your pH.

My replaster job (Diamond Brite) is now 6-7 weeks old, and it's in perfect condition. WATCH YOUR CSI !!!

Thanks for the response, yeah it looks like i should just go by TA like you did. I just tested my tap water with water softner on and off and my CH was 0, i tested four times just to be safe.

 

[FLDude]

Unless your CYA is very high, like over 100ppm, then the adjusted alkalinity and total alkalinity will be very close.

How are you chlorinating the pool and what have you added to chlorinate with? What is your current CYA level?

Waiting 24 hours to adjust CH is fine. You can't possibly do damage to your plaster in that time frame unless you do something royally stupid like pour in gallons of acid. Once the plaster is troweled and the aggregate is exposed, there is still some plaster cream left on the surface that will dissolve into your pool water and cause the CH to rise. Waiting 24 hours gives it time to do that. Again, the amount of calcium lost in that 24 hour waiting period really is insignificant.

ALWAYS, ALWAYS, ALWAYS adjust CH slowly and in small batches. Calcium chloride (CH increaser) can cause serious clouding of the pool if it is added too fast.

I wouldn't focus too much on holding EXACT values of TA. If your pH gets to 8, knock it down to 7.6 and then wait. Let the TA settle wherever it will. In these early days, the TA is going to remain elevated because of the fresh plaster. Just keep the pH in a good range and monitor the TA. If it falls significantly below 80ppm, then bump it up with small additions of baking soda.

So they just finished chipping out the pool yesterday so no water in there yet. I planned on using liquid chlorine from pinch a penny which is what ive been using to chlorinaye the pool since i got it. Thanks for the tips, sounds like i just need to go with TA and add ch slowly.

I tested my fill water today with and without water softner bypassed and here are my results, they were the same with softner on and off except ph was 8.06 when the softner was on.

Ph = 7.9
Ta = 120
Ch = 0
Cya = 0

 

[FLDude]

Your CYA should be a maximum of 30 so 1/3 of CYA is 10. So the difference between TA and Carbonate Alkalinity is 10. That is 1 drop of testing.

They ask your Carbonate alkalinity to be between 80 to 120 ppm.

So keep your TA between 90 and 120 and don't worry about the carbonate alkalinity adjustment. It really is not material and within your testing error for alkalinity.



Wait for the second day to adjust your CH. You need to give the plaster time to cure.

The whole thing that PDF is driving you towards is on the second page where the targeted LSI is 0 to +0.3.

Our plaster expert, @onBalance , says...

It is actually necessary, to achieve a smooth and dense surface, to have about a +0.5 CSI during the first 30 days. This is because the plaster (cement paste) surface contains about 20% calcium hydroxide, which is somewhat soluble in balanced and slightly positive CSI water and can be dissolved away. The plaster surface needs to be "carbonated" before the CSI should be lowered to the acceptable and balanced range. And that generally is achieved during the first month under balanced water

CSI and LSI - Further Reading

www.troublefreepool.com

The web page says:

Adjustments requiring more than 20 lb. of CaCl^2 should be pre-diluted and added in 10lb increments – morning and afternoon.

So do the adjustments in a maximum of 10lb increments.


Reduce your pH in increments of 0.2-0.3 and it will not effect your TA much.

Don't reduce your pH below 7.6.

Thanks for such a detailed response, i really appreciate it. Yeah so doing my research over the last few weeks i learnt that LSI is something that you should pay attention to when maintaining the pool not on start up, is that right?

 

[mknauss]

Why do you need a water softener if your raw source water has 0 CH?
I suspect you need to find a non softened source for your fill water.

 

[ajw22]

Yeah so doing my research over the last few weeks i learnt that LSI is something that you should pay attention to when maintaining the pool not on start up, is that right?

We use CSI which is simply calculated when you use PoolMath. Turn on CSI tracking.

CSI and LSI - Further Reading

www.troublefreepool.com

Calcium Saturation Index (CSI)

How is CSI calculated? Very simple – use our PoolMath tool. To ensure long plaster life and save money, click here to learn more.

www.troublefreepool.com

 

[FLDude]

Please test your tap water (or fill water that will be filling the pool) and let us know what the alkalinity, calcium hardness, and pH is, and we will be able to provide better guidance for you.

No problem, i have a water softner and just tested twice with it on and twice bypassed and the test results were exactly the same except the ph with the water softner on was 8.06.

Here are my results with the softner off:

Ph = 7.9
Ta = 120
Ch = 0
Cya = 0

Is it normal to have no ch in my water?

 

[FLDude]

Why do you need a water softener if your raw source water has 0 CH?
I suspect you need to find a non softened source for your fill water.

It came with the house and i just moved here in July so i have no clue. Ch with the water softner bypassed was 0, is that going to be a problem then if i use it as fill water?

 

[mknauss]

Did you run the faucet for several minutes after bypassing the softener?

You do NOT want to do your initial fill with softened water.

 

[ajw22]

If you have to use that tap water to fill the pool consider using the BiCarb Startup developed by @onBalance . It has you balance the tap water before it enters the pool so that brand new plaster is protected from being dissolved and losing some cement material from the surface.

A Bicarb Start-up guide for TFP members

It is an unfortunate fact that most tap water used to fill swimming pools is often soft, aggressive, and somewhat harmful to a new plaster surface. Therefore, in order to not damage a new plaster surface, the tap water needs to be “balanced” (meaning for new plaster, the CSI should be at least...

www.troublefreepool.com

 

[proavia]

Find an outside hose bib - probably near where your water main enters the house - and test the CH using that water. Post a pic of where the water main enters the house and also a pic of your water softener setup.

Does the water softener use salt?

 

[FLDude]

Yeah so im an idiot, i didnt flip all the bypass valves on the water softner setup.

Here are my results with the softner bypassed. I ran the tap for about 5 minutes to be safe.

Ph = 8.22
Ta = 100
Ch = 100
Cya = 0

 

[mknauss]

Good. With that initial fill water, you will need to source some calcium chloride. No rush, just keep the TA in the higher range and do not aggressively lower the pH.

 

[FLDude]

Good. With that initial fill water, you will need to source some calcium chloride. No rush, just keep the TA in the higher range and do not aggressively lower the pH.

Thanks for the advice. Whats the reasoning behind not aggressively lowering ph? Also is going from 8.2 to 7.4 considered agressive? Instead should i go down .2 or .3 at a time like suggested above?

 

[mknauss]

You want to manage CSI during start up. The low CH means you need higher pH and TA. I would not lower pH by more than 0.4 at a time. And only when it gets to 8 or above.

 

[ajw22]

Thanks for the advice. Whats the reasoning behind not aggressively lowering ph? Also is going from 8.2 to 7.4 considered agressive? Instead should i go down .2 or .3 at a time like suggested above?

See the discussion above about keeping your LSI/CSI positive around+0.3-+0.5.

Lowering your pH lowers the LSI/CSI which is not what you want.