New to pools and new plaster...

[conk12301]

Hi all -

We renovated the plaster on the pool at our new home this spring. Never had a pool before, only a hot tub. So I'm only mildly comfortable checking and adjusting Ph/Alk. Add in the new plaster as a complication and I'm getting confused.

When they finished the plaster, the service guy told me to use muriatic acid to bring the PH down to 7.2-7.4 Did that for a couple days, and it would always shoot back up. Muriatic acid also sent the alk down. I know in my hot tub low alk can mean PH swings, so I ditched the muriatic acid. Tried Alkalinity increase to get that stable and then dosed with PH down. Been working off that strategy that for a few days and alk stays stable at 80-90 but every 24 hours the PH still seems to jump back up to 7.8-8.2 range.

The service guy said its crucial we keep new plaster at 7.2-7.4.

So a few questions --
Is it normal to have to dose the Ph down so frequently?
Plaster was finished about 10 days ago. Should I go back to muriatic acid? Should I keep trying to use PH down?
Also, when I brush the pool 2x as instructed, I noticed there's still a good amount of plaster dust on the bottom... how long should this last?
Why is 7.2-7.4 the rule for new plaster? Is high PH going to ruin my plaster or prevent it from curing in some way? Worried I am screwing this up already.

Thanks - any help would be greatly appreciated!

 

[.ben]

The curing process for brand new plaster will cause constant pH rise. From what I’ve read this process can last 6-12 months+.

For reference, I use about 1/3 gallon of MA every 2-3 days and my plaster is almost 4 months old. Earlier I was using 1/2 gallon every 2-3 days.

I recommend finding the best local price for MA because you will need to buy a ton. For me, Lowes and Home Depot sell 2 gallons of 31.45% for $17.

I had plaster dust for at least 3-4 weeks. Keep brushing and running your pump 24 hr/ day.

 

[conk12301]

The curing process for brand new plaster will cause constant pH rise. From what I’ve read this process can last 6-12 months+.

For reference, I use about 1/3 gallon of MA every 2-3 days and my plaster is almost 4 months old. Earlier I was using 1/2 gallon every 2-3 days.

I recommend finding the best local price for MA because you will need to buy a ton. For me, Lowes and Home Depot sell 2 gallons of 31.45% for $17.

I had plaster dust for at least 3-4 weeks. Keep brushing and running your pump 24 hr/ day.

This makes me feel a lot better. Thanks!

So I guess I should just switch back to MA since that is stronger to keep the PH down. How will you know when to switch to regular chemicals rather than MA? Or do you plan to do MA indefinitely?

 

[ajw22]

Muriatic acid also sent the alk down. I know in my hot tub low alk can mean PH swings, so I ditched the muriatic acid.

What test kit are you using?

TA down to 50 is ok and does not lead to pH swings. Lower TA will give you a slower pH rise.

TA - Further Reading

www.troublefreepool.com

PH TA Relationship - Further Reading

www.troublefreepool.com

Tried Alkalinity increase to get that stable and then dosed with PH down.

We do not recommend the use of dry acid. Dry acid contains sulfates which will accumulate in the water. Dry acid should not be used in plaster pools or pools with a SWG.

Read - Acid - Further Reading

Is it normal to have to dose the Ph down so frequently?

Yes, your pH is not going to stay down at 7.2-7.4 for long.

What is your TA?

Plaster was finished about 10 days ago. Should I go back to muriatic acid? Should I keep trying to use PH down?

You should be following your plaster startup guide for the first 30 days. Do you have one you are following?

Plaster Start-Up Guides - Further Reading

www.troublefreepool.com

Also, when I brush the pool 2x as instructed, I noticed there's still a good amount of plaster dust on the bottom... how long should this last?

Are you running your pump/filter 24/7?

Why is 7.2-7.4 the rule for new plaster? Is high PH going to ruin my plaster or prevent it from curing in some way? Worried I am screwing this up already.

Well we have different recommendations for startup that don;t just focus on pH.

You may also be interested in Plaster Installation threads that contains tips like this:

• The CSI is not applicable to new plaster finishes under 30 days old. 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.[

 

[conk12301]

What test kit are you using?

TA down to 50 is ok and does not lead to pH swings. Lower TA will give you a slower pH rise.

TA - Further Reading

www.troublefreepool.com

PH TA Relationship - Further Reading

www.troublefreepool.com

We do not recommend the use of dry acid. Dry acid contains sulfates which will accumulate in the water. Dry acid should not be used in plaster pools or pools with a SWG.

Read - Acid - Further Reading



Yes, your pH is not going to stay down at 7.2-7.4 for long.

What is your TA?



You should be following your plaster startup guide for the first 30 days. Do you have one you are following?

Plaster Start-Up Guides - Further Reading

www.troublefreepool.com

Are you running your pump/filter 24/7?




Well we have different recommendations for startup that don;t just focus on pH.

You may also be interested in Plaster Installation threads that contains tips like this:

• The CSI is not applicable to new plaster finishes under 30 days old. 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.[

All good info... thank you so much!

I read through the plaster start up thread once I found this forum today. Service guy didn't give me a ton of info beyond initially dosing with MA and then keeping PH down from there. So I started with MA and then switched to Ph Down and Alk increaser since that's what I was familiar with from my hot tub. But it sounds like I should stick to MA for awhile.

Didn't realize TA as low as 50 will still act as buffer. Great to know. And filter is running 24-7. Test kit is Leslie's Pool Deluxe.

Couple more questions -
- My TA is currently 80 ppm and PH at 7.6. I went back to a small dose of MA. Going to continue on with that. Should I expect to use that my entire first season with the new plaster?
- Service guy said no shock for 30 days but had me start with chlorine tablets in the floater. I noticed chlorine is <1 ppm though. Probably because of all the sun the last two days. Should I be using stabilizer yet?

Again - thank you so much. Feeling a little less lost lol.

 

[ajw22]

My TA is currently 80 ppm and PH at 7.6. I went back to a small dose of MA. Going to continue on with that. Should I expect to use that my entire first season with the new plaster?

You never know which way things go with pH in a plaster pool. You just deal with whatever way the pH goes.

- Service guy said no shock for 30 days but had me start with chlorine tablets in the floater. I noticed chlorine is <1 ppm though. Probably because of all the sun the last two days. Should I be using stabilizer yet?

My recommendation is pull the tablets from the pool.

All startup guides say to add 30 ppm of stabilizer after day 4.

Use liquid chlorine and keep your FC at 2-3 ppm.

Get a better test kit. Either the Taylor K-2006C or TF100 Test Kits

It is important with new plaster to get the correct calcium level.

 

[ajw22]

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