Ph and TA and how to reach stability

[bigjohns97]

I have a constantly running trickle down effect from my raised spa going into my pool as well as a waterfall feature that I only run a couple hours each weekend or when we have people over.

I have noticed that every time I run the waterfall feature that my Ph raises and after a while of dumping MA to keep the Ph under 8 I notice my alkalinity starts to get really low.

Now I came across this thread

How do those with waterfalls deal with high PH

Aeration obviously raises PH. For those with waterfalls or fountains or other nice add-ons that contribute to natural aeration, how do you deal with your PH? Assuming you have your alkalinity in check, does your PH remain at an appropriate level regardless of aeration? Or, does it rise and...

www.troublefreepool.com

Specifically this post

"This is why when people experience pH rise form aeration, we first tell them to lower their TA and try to find a TA level that minimizes the frequency of acid additions. Sometimes their acid demand problem can be solved simply by lower TA, sometimes it can't and then borates are recommended. So, in your case, rather than running off and buying expensive chemicals, why don't you first run your aerator/fountain for a while and see what happens. You may not, in fact, experience much pH rise at all. Even if you do, your first order of business is to lower your TA to try to correct the problem, not add borates."

And this post

"This is why I keep my TA down in the 50ish range. It has slowed my acid additions greatly."

Well now my TA is down in the 40's and I my Ph is at 8 again and I am about to pour another glug of MA into the pool to get the Ph back down to 7.6 and probably take the TA down to well below 40's.

My question is how do I stop this madness, surely at some point the alkalinity becomes a problem outside of just leading to acidic water right?

Please help.

 

[AK-]

What is your current TA?

Have you read?

Managing pH and Total Alkalinity - Further Reading

www.troublefreepool.com

 

[bigjohns97]

What is your current TA?

Have you read?

Managing pH and Total Alkalinity - Further Reading

www.troublefreepool.com

I have not but here is what I picked up from it.

I need to keep my TA above 50 even though the only reason why it says to do this is to keep my pH from crashing which I don't have the problem of because I still have too high of a pH.

So I guess that is still my question, it seems that with an Alkalinity below 50 I shouldn't have rising pH like I do especially with only running the water fall for a couple of hours a week.

Surely this can't all just be the trickle from my spa to my pool?

 

[Rancho Cost-a-Lotta]

What's the TA and pH of your fill water? Are your reagents fresh?

 

[SoDel]

The “theory” is at each level of TA and temperature there is a pH ceiling and under Henry’s law of solubility of gasses (including CO2 which drives our pH), due to proportionality, the rate of rise of pH slows as you approach that ceiling. So for example, typical pool chemistry with a TA of 40 ppm and temp of 80 degrees F, pH ceiling is 8.03. The rate of pH rise as you approach that ceiling should slow considerably. Leads to questions — over what period of time does the pH rise from what to what? Do you have a SWG?

IMHO, low TA is not an issue and you should offset it with high CH and pH management (to maintain appropriate saturation index). Some research that has been kicking around for decades recommends this approach to better preserve your plaster and equipment (.pdf includes two articles, both worth reading).

https://cdn2.hubspot.net/hubfs/3831534/LSI%20index%20impact%20of%20calcium.pdf

 

[jark87]

I received the same recommendation - lower TA to help combat pH rise. I found that TA in the 50-60 range works best for my pool and it has slowed my pH rise, but I still add acid about once a week. I also have to keep an eye on CSI with the lower TA. I use a chiller to keep temps low, but I think the way it works with water trickling down over baffles and into a tub adds aeration, so any gain I make with keeping temp lower is offset by the added aeration. I just live with the fact that pH has to be managed with my pool.

 

[bigjohns97]

I received the same recommendation - lower TA to help combat pH rise. I found that TA in the 50-60 range works best for my pool and it has slowed my pH rise, but I still add acid about once a week. I also have to keep an eye on CSI with the lower TA. I use a chiller to keep temps low, but I think the way it works with water trickling down over baffles and into a tub adds aeration, so any gain I make with keeping temp lower is offset by the added aeration. I just live with the fact that pH has to be managed with my pool.

So do you ever add anything to raise TA because you feel it is getting too low?

 

[bigjohns97]

What's the TA and pH of your fill water? Are your reagents fresh?

I ended up having to fill about a month ago and TA was up around 130, pH was about 8.0 but I haven't tested the water completely on it's own.

I don't think my reagents are bad, double checking against Leslie's water check seems to suggest they are good (at least for the things Leslie's doesn't manipulate).

BTW I recently stopped going to Leslie's and ordered my own phosphate kit, I had no idea home depot had the same stuff for half the price

 

[bigjohns97]

What is your current TA?

Have you read?

Managing pH and Total Alkalinity - Further Reading

www.troublefreepool.com

Finally getting time to come back to this thread and re-read this document and I am taking this at face value of this first statement.

"In the relationship between Total Alkalinity and pH, pH should be your focus. Keep it between 7.0 and 8.0. Let Total Alkalinity be what it may. If you are constantly and frequently adding Acid, then Lower Total Alkalinity. Otherwise, manage pH an ignore TA."

However if I keep reading it says multiple times that TA below 50 is really bad, with me using liquid chlorine exclusively now (CYA issues and tired of draining / refilling the pool) I am constantly fighting rising pH.

 

[mknauss]

Can you share your Poolmath data or post a full set of current chemistry data?

 

[bigjohns97]

Can you share your Poolmath data or post a full set of current chemistry data?

Cl 5
pH 7.6
TA 60
Ch 270
CYA 50

BTW currently this is the most stable I have seen my pH since draining and filling over a month ago, I have only put in a half gallon back on Monday and that brought it from 8 down to 7.2 but it has been very stable since that and I have added 4 gallons of 10% liquid Chlorine since Monday.

I am thinking once I get down to 50 I might actually be fully stable at 7.2 which would allow me to run my waterfall on a schedule to balance between 7.2 and 7.6 which is what would be the best case scenario (I want to run the waterfall rock to keep the water temp down).

 

[mknauss]

I would just keep the pH in the mid to upper 7's. Your CH level is such that CSI can be a bit too negative if you push TA down further and/or keep pH in the low 7's.

 

[bigjohns97]

I would just keep the pH in the mid to upper 7's. Your CH level is such that CSI can be a bit too negative if you push TA down further and/or keep pH in the low 7's.

I see what you mean, going to a TA of 50 really moves the CSI to -.2 and then I would have to really stay on top of the rock water fall which I am okay with cause the more it runs the cooler the water stays.

We'll see after a couple more applications of liquid chlorine if the pH goes to 8 again I will have to apply MA to bring it back down.

So far I haven't been able to run the rock waterfall once because the pH always rises on its own.

Hopefully getting close to a steady state, will keep an eye on poolmath and the CSI factor, thanks everyone!

 

[mknauss]

Liquid chlorine does not raise the pH. The process of it through the cycle is pH neutral.

 

[bigjohns97]

Liquid chlorine does not raise the pH. The process of it through the cycle is pH neutral.

I saw that article too but everyone keeps telling me it raises pH

Either way (if it's the LC or the constant trickle over from spa to pool) neither are changing so I still have to stabilize my pH by using a non-standard (per some) lower TA.

Hopefully this TA of 60 is where it lands, I am tired of purchasing 2 gallons of MA every two weeks with my LC.

 

[mknauss]

everyone keeps telling me it raises pH

Follow the science -------

 

[drewwestrick]

I’m seeing similar things when it comes to increasing PH. At first, I attributed the PH rise to a very high TA (local water is ~220-250). The last few weeks, I’ve been able to bring my TA down to about 70 with regular acid and aeration (intentionally pointing the returns up, running pump continuously). The only difference with OP is I don’t have any water features or things that would obviously contribute to aeration (unless I adjust the returns). Is it common for people to add acid about twice a week? I generally add acid once PH get to 7.9 or 8.0. Adding 16 oz usually brings it down to 7.6. Right now, I usually see about 0.1 PH rise a day. It feels like it slows down and wants to rest at about 8.1 or 8.2. Once I let things stabalize a little more, should I consider adding Borates or just accept that I’m going to need a little Acid every few days if I want to stay in that 7.6-7.8 sweet spot? Feel free to take a look at my logs.

 

[mknauss]

Are you adding any of the high TA fill water?

 

[drewwestrick]

Today was the first time I’ve added fill water since they originally filled the pool 25 days ago. We don’t have have the auto cover on yet so the water level has come down an inch or two in that time which I added back today. TA went up a little which was expected as the fill water is high TA.

 

[mknauss]

A CYA of 20, means nearly all your TA is carbonate alkalinity. If you believe you can keep your CYA at that level, you may need to take TA down to 40 ppm for pH to be more stable.