pH keeps rising, alkalinity low

[Tegguy]

Evening everyone hoping for a sanity check to make sure I'm doing the right things. Been testing regularly and logging the results in poolmath and I've noticed I'm adding acid about twice a week to keep the pH down. Until today my alkalinity was in a good range but tested at 50 today. So I have a couple questions

1) is it normal to keep having to add acid (9 month old pool)?
2) did I make the right call in adding acid today even though alkalinity was low?
3) is the alkalinity too low?

Pool looks great color wise.

Side note I saw my CC's were elevated slightly today around 1 but I don't think it's anything to worry about.

Thanks

 

[mknauss]

Are you running your spa spillover all day?

 

[JamesW]

If the pH is not over 8.0 and the CSI is not over +0.1, then I would leave the pH alone.

If the pH is over 8.0, I would get it down to 8.0 or 7.9.

If the CSI goes above +0.1, then I would lower the pH enough to get the CSI below +0.1.

 

[Tegguy]

Are you running your spa spillover all day?

Yes we are but it's a very small amount of water (or do it seems). It's a large spill over with a slow pump speed.

 

[Tegguy]

If the pH is not over 8.0 and the CSI is not over +0.1, then I would leave the pH alone.

If the pH is over 8.0, I would get it down to 8.0 or 7.9.

If the CSI goes above +0.1, then I would lower the pH enough to get the CSI below +0.1.

It seems like every 3 days I'm lowering the pH from 7.9-8.0 down to 7.2-7.4.

 

[JamesW]

It seems like every 3 days I'm lowering the pH from 7.9-8.0 down to 7.2-7.4.

If the pH is not over 8.0 and the CSI is not over +0.1, then I would leave the pH alone.

If the pH is over 8.0, I would get it down to 8.0 or 7.9.

If the CSI goes above +0.1, then I would lower the pH enough to get the CSI below +0.1.

 

[Tegguy]

@JamesW Understand but if I'm trying to keep the pH under 8.0 I have to go lower than 7.9 to keep from song acid everyday. It's rising ~.7 in three days or so> the pH is not stable

 

[JamesW]

Understand but if I'm trying to keep the pH under 8.0 I have to go lower than 7.9 to keep from song acid everyday.

It seems intuitive to do it that way, but what you are doing is actually making it worse.

Lower pH creates a lot of carbon dioxide, which offgasses and raises the pH.

Lower pH also reacts more with with the plaster to release calcium hydroxide and calcium carbonate both of which raise the pH.

Although it is counterintuitive, lowering the pH less actually works better.

As long as you follow the guidelines that I posted, the amount of acid will be minimized.

 

[mknauss]

Agree with JamesW. You can also reduce the spillover time. Your Intellicenter is a very capable automation system. Utilize its features.

 

[Tegguy]

It seems intuitive to do it that way, but what you are doing is actually making it worse.

Lower pH creates a lot of carbon dioxide, which offgasses and raises the pH.

Lower pH also reacts more with with the plaster to release calcium hydroxide and calcium carbonate both of which raise the pH.

Although it is counterintuitive, lowering the pH less actually works better.

As long as you follow the guidelines that I posted, the amount of acid will be minimized.

I always thought lower pH was better but it sounds like I'm wrong I was worried about the pH going to high (above 8.0) but it sounds like it happens to go above 8 it's not detrimental just bring it back to high 7's and watch the csi.

I'm currently testing 2x per week due to pH and if love to get back to once a week if possible.

 

[Tegguy]

Agree with JamesW. You can also reduce the spillover time. Your Intellicenter is a very capable automation system. Utilize its features.

Roger that the spillover is the valve stop position for pool to keep the pool returns running as well. I don't have a special setting for spillover currently.

 

[JamesW]

The main thing is to not let the CSI get too high.

As long as the CSI is not going above +0.10, you should be fine.

 

[Tegguy]

The main thing is to not let the CSI get too high.

As long as the CSI is not going above +0.10, you should be fine.

Ok thank you both for the help. Should I ask baking soda tomorrow to get the alkalinity up or let it be for now?

 

[JamesW]

Ok thank you both for the help. Should I ask baking soda tomorrow to get the alkalinity up or let it be for now?

As long as the CSI is between -0.3 and +0.1, I would leave everything alone.

Sometimes people try too hard to adjust the chemistry and they end up doing way too much work.

 

[Tegguy]

@JamesW I just wanted to make sure I understand your recommendation correct

Just did the water test pH was 8.0, alkalinity was 50, csi was -.09. you would recommend not changing anything correct?

 

[JamesW]

@JamesW I just wanted to make sure I understand your recommendation correct

Just did the water test pH was 8.0, alkalinity was 50, csi was -.09. you would recommend not changing anything correct?

I would not do anything.

As long as the CSI is fine and the pH is not above 8.0, I would leave it alone.

If the pH hits 8.1, lower it to 8.0.

 

[Tegguy]

I would not do anything.

As long as the CSI is fine and the pH is not above 8.0, I would leave it alone.

If the pH hits 8.1, lower it to 8.0.

Thank you