Just getting familiar with new pool... high TA and pH levels

[rhosch]

Hopefully my sig shows up. I need to go look up specifics of pump, filter, etc.

Using TF-100 test kit and salt test kit from Taylor recommended here (1766 maybe?). Pool builder has been maintaining (?) chemicals after construction was finished late last year while working out a few kinks in plumbing and getting final inspection done. Just transitioning into my care and so I'm getting up to speed on testing and maintaining chemistry myself.

Initial test results showed salt low at about 2400, FC very low at 0.5, CYA essentially zero, pH high at 8.2, and TA very high at 270. Guess the pool builder hasn't been too concerned with chemistry!

Haven't had an algae bloom (yet) but I did add significant bleach to get FC near SLAM levels. No CC initially and seems stable overnight, letting that drift back down slowly. Added CYA and got that up to 60.

Added HCl to drop pH which... had little effect. I'm guessing because of the very high TA level? I've been doing some reading on high pH of SWG pools, and the effect of aeration. I have two spills and the infinity edge that drops 4 ft, so aeration I have in spades. Those water features run 14 hours per day currently (pool builder settings). I can turn spills off independently, but it's tough to turn off the infinity edge. I can, but it is a manual process, and when it is circulating only the main pool the catch pool is stagnant. Also, it's a little tough to maintain water levels as I think there is only an autofill on the catch pool, so if I circulate just the upper and get evaporation from both, then switch back to infinity flowing over, there is a risk of pulling air into the pump. Done that a few times, had to add water manually at that point. So, it's been easier to just let it always flow over.

All that brings me to my question - with a SWG and significant aeration from the water features, what is going to be my best method(s) to keep pH and TA in check? I've read about adding borax as a buffer and that sounds like it may be reasonable to do. Any other suggestions?

I'm in the process of adding salt to get that level up, and have been adding muriatic acid a gallon at a time watching pH barely budge measured half a day later.

 

[ajw22]

Welcome to TFP.

What is the pH and TA and CH of your fill water?

Borates is not a magic bullet for your pH problems. You should not consider borates until you have your pH and TA well under control.

Test your pH 15 minutes after adding muriatic acid to see what you lower it to.

When your pH gets to 8 lower it to 7.2. Every time you do it it lowers your TA a bit. See if you can get your TA down to 60 to 70.

The way you designed your pool it will be a constant pH problem. Stock up on MA.

Lower Total Alkalinity

A lower Total Alkalinity level can help a pool owner stabalize their pH increase. We'll explain how to lower TA with a little help from muriatic acid.

www.troublefreepool.com

​

 

[rhosch]

Thanks, I'll check my water supply chemistry and report back.

Never thought about the pool design's effect on water chemistry during planning, but then again I've never been a pool owner before. It does sound like the constant hyperaeration will be a constant struggle but... I'd probably design it the same again anyway. The view just screams for it and we are thrilled with how that turned out.

I probably need to work on trimming the pump hours back some too, early morning would be a good starting point. Every little bit help I'm sure.

 

[CrystalRiver]

You're right that borates act as a buffer - they'll resist any change, up or down. Don't even think of introduction them until your pH and TA are at your target levels, or you'll just make it that much harder (and more expensive, in additional acid) to get your levels correct.

It's possible that your acid additions are lowering your pH, but the high TA combined with aeration are letting your pH climb before you test again. Or, it's possible that your pH is much higher than you think, because it is off the scale. And every number on the scale is 10x higher than the one before - pH 8 is 10x more basic than pH 7, and pH 9 is 100x more basic. If your pH is actually closer to 9, it may take 10x as much acid as you would think it needs.

All of that is why she suggested you test again shortly after adding acid. That will let you know if you are reaching your target and it's bouncing back up, or if you never reached your target at all. If you never reached it, then it's worthwhile to spend a few hours adding and retesting every 15 minutes until it reaches your target. Then see how long it takes to bounce up again.

 

[rhosch]

Thanks, yeah that makes sense. Using the pH scale in the TF-100 kit, I could see how anything above the top of that scale might just look pretty similar in color. I'll be gone for the first part of today, hopefully this afternoon I can do some more testing and see where things stand.

 

[rhosch]

OK, my fill (tap) water is:
TA 160
pH 8.2 (or more, matches top color on K-1000)
CH essentially 0 (blue without adding any of the second drops)

My pool TA was down to 240 today
CH is at 125 (a little surprised as its a new plaster pool - assumed it would be Ca rich to start?)
pH 8.2+
This after some moderate rain this afternoon

I added MA to lower pH to ~7.2 according to pool math (1 gallon), slowly distributed to all of the returns and spills. Retested 20 minutes later and pH matches 7.5.

I'll see how long it takes for pH to creep back up to 8.0. If that happens in say, one day, is there any harm in adding a gallon of MA per day if that is what it takes? Of course, I'm hoping that slows down and stabilizes at some point!

 

[HermanTX]

OK, my fill (tap) water is:
TA 160
pH 8.2 (or more, matches top color on K-1000)
CH essentially 0 (blue without adding any of the second drops)

With your tap water at Zero CH indicates you have a water softener. That is fine but that is why your pool water is low on CH because no calcium is being added when you add fill water.

 

[ajw22]

OK, my fill (tap) water is:
TA 160
pH 8.2 (or more, matches top color on K-1000)
CH essentially 0 (blue without adding any of the second drops)

This fill water will make it difficult to ever keep your pH or TA down.

Do you have an autofill?

Even if you lower your pH and TA it will rise every time you add water due to evaporation.

My pool TA was down to 240 today

I have to wonder how your pool TA got to 270 when your fill water is 160. TA does not rise naturally.
It takes chemical additions to raise TA, especially that much.

CH is at 125 (a little surprised as its a new plaster pool - assumed it would be Ca rich to start?)

With 0 CH in your fill water you should raise the CH in your pool up around 300.

pH 8.2+

Add MA anytime your pH is not in the 7's.

This after some moderate rain this afternoon

Rain makes no significant difference to your pH.

I added MA to lower pH to ~7.2 according to pool math (1 gallon), slowly distributed to all of the returns and spills. Retested 20 minutes later and pH matches 7.5.

You don't need to distribute the acid like that. Pour it into one place and then brush that area with your pool brush to stir the acid into the water and keep it from pooling on the plaster.

You may have your pool volume set too low if PM predicted 7.2 and you got 7.5. UP your pool volume to 35,000 gallons and see if the acid amount gets you more to the target pH that PM pedicts.

I'll see how long it takes for pH to creep back up to 8.0. If that happens in say, one day, is there any harm in adding a gallon of MA per day if that is what it takes? Of course, I'm hoping that slows down and stabilizes at some point!

No, keep on adding acid as often as needed to lower your pH from 8 to 7.2. Keep an eye on your TA and stop when your TA gets to 60, if you ever get it that low.

 

[rhosch]

I don't know what caused the TA to get to that level. Don't know as in, the pool builder has been adding various chemicals late fall, over the winter and early spring. I'm only just now taking over chemistry so I don't know what led to the current state. I probably should, but don't

Good to know adding MA can be done a little quicker. The HCl vapors are some nasty stuff, I'd rather get it in then start it mixing underwater. I'll try that next time.

There is an auto fill on the lower catch pool. And yeah - our tap water isn't great. It looks like weak tea. Yay.

Sounds like with the SWG and lots of aeration I get my pH is going to be constantly rising and I'll constantly be adding MA. I guess the fill water will contribute to pH rising but maybe the MA will help keep the TA in check? I can hope at least.

We don't use any sort of whole house water softening or anything. That's just what comes from the street. I'll test again to make sure.

On the pool volume, chlorine and CYA seemed to land where predicted. I wonder if pH was just above 8.2? I wonder how much color changes above the range the k-2000 is calibrated for? Maybe it was just 8.5 to start. I'll keep an eye on it - maybe I do need to adjust the volume some.

 

[ajw22]

Are your catch pools and basins included in your pool water volume?

 

[ajw22]

Your pool may be a candidate for pH control using CO2. Read….

Poolsmith CO2 injection for pH control

Doesn't appear to be much discussion about this system on the forum. Am seriously considering ordering one of these. I'm typically adding about a quart of acid every 3 to 4 days in my 20k gallon SWG pool. Not a lot of fun, plus if we travel for more than a week or so I need to hire someone to...

www.troublefreepool.com

 

[rhosch]

I did include the catch pool in total volume.

I read through that CO2 thread. Interesting. I'm hoping that as I get TA down and plaster cures cometely my pH rise will slow down a bit. I don't mind adding acid so long as it isn't a gallon a day! Good to know there may be other options.

 

[IceShadow]

TA could be higher than the fill water due to evaporation + refilling. The evaporation leaves the TA behind, fill water adds more - over time it will be higher.

So long as the pH is down in the 7s it is safe on equipment and swimming (from a pH perspective). You'll be adding a lot of muriatic acid over time, but I'm sure the TA will come down as you go. It might be worth investigating a solar cover to cut down on evaporation so that you're not refilling with the higher TA water and moving backward.

 

[rhosch]

Thought I'd post an update, it's been 10 days. I've added 7 gallons of MA in that span and TA has crept down to 160. Have some work left to do. When it gets in the recommended range then I will have a little better idea how fast my pH will really rise and can consider adding borates at that time. From discussions in another thread here, I think I'm going to replace the valve that selects main pool or infinity edge catch pool drains (effectively "turning off" the infinity edge if pulling water from the main pool) with an automated valve so that the infinity edge doesn't run at night. Cutting my aeration down some can't hurt.