Do I have to consistently add Muriatic Acid to balance salt water pool PH level?

[joshuazzx]

Dear Experts,

I have been maintain my 16000 gallon salt water pool myself and have a few questions below.

1. As the Chorine will be burn by the Sun and the Chlorinator is producing Sodium Hydroxide while generating Chorine, so the PH will always increase, hence I have to add Muriatic Acid consistently to control PH not being too high. Is my understanding correct?

2. If so, What is the typical frequency of adding Mauriac Acid? I found I have to add every 3-4 days. Is it normal?

3. If I decide to add borate, will that help slow the increase of PH?

Thank you

 

[Newdude]

Is my understanding correct?

Kinda not kinda. SWGs are PH neutral in the end.

The extended pump runtimes to produce enough FC for the day is generally longer aeration than people had prior, making the PH rise the SWGs fault, when it's really the pumps fault.

Or they switched from tabs which were CY(Acid) so without constant acid adds, the PH rise again is wrongly blamed on the SWG.

If so, What is the typical frequency of adding Mauriac Acid? I found I have to add every 3-4 days. Is it normal?

We can probably tweak yours. Lower the TA to 60 by running the PH in the low 7s for a while.

Then switch to keeping the PH in the high 7s. When it hits an 8, lower it but only to 7.6 or 7.8.

It will likely be more stable that way, lasting a week or more at a time.

If I decide to add borate, will that help slow the increase of PH?

Probably. But it's funny. You'll likely need twice as much, half as often. But half the work is still nice.

Try the TA and PH tweaks first and see where you land.

 

[mgtfp]

Creation of one Cl2 molecule in the SWG-cell comes with two OH-. As the Cl2 dissolves into the water, forming one HOCl and one Cl-, one H+ gets released which compensates the first of two OH-. Once the HOCl gets "used" by UV or oxidising "stuff", turning the Cl into Cl-, another H+ gets released, compensating the second of the two OH-.

The complete chlorination cycle with a SWG is pH-neutral.

But in the meantime, parallel occuring CO2 outgassing has lead to a rise in pH. To minimise this, do what Newdude recommended.

 

[joshuazzx]

We can probably tweak yours. Lower the TA to 60 by running the PH in the low 7s for a while.

Then switch to keeping the PH in the high 7s. When it hits an 8, lower it but only to 7.6 or 7.8.

It will likely be more stable that way, lasting a week or more at a time.

Thanks a lot. Basically what recommended is to lower the TA to slow down the increase of PH? I will try that.

My CYA is at about 50, do you think it will help if I increase to 80 thus I can reduce the pump running time. My pump runs from 8am to 7pm every day.

 

[wireform]

For your location 70-80 CYA is appropriate this time of the year which will protect the chlorine a bit more thus not letting UV get to it as easily. Pump time is dependent on how long you need to run the SWCG to make up your daily loss. You can run it say 100% for 5 hours or 50% for ten hours and have the same FC output but that's entirely up to you.

 

[Newdude]

My CYA is at about 50, do you think it will help if I increase to 80 thus I can reduce the pump running time.

I think you'll likely need 80 because TX, but let's take one step at a time.

My pump runs from 8am to 7pm every day.

How long is the SWG set for ?
What % ?

We can reverse engineer your apporximate daily loss from that data and your testing. That will tell us if you should raise the CYA. (After passing an Overnight Chlorine Loss Test)