10 years of pH bounce getting real aggravating

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mikemass

mikemass

0
Jul 10, 2013
490
Northern Howell, NJ
First off let me state pool is always crystal clear. Visually it is great. Minimal scale which I will knock down with a pumice stone once I get in the pool. But these darn readings! I am almost at a point of saying heck with it and if the water looks good just let it be.

This pool is IMPOSSIBLE to keep the pH in an acceptable range. I can't even imagine the amount of money I have spent on Muriatic Acid over the years. I opened the pool Sunday (today is Wed). Without even testing (because I know my pool), I dumped in 1 full gallon of the blue bottle (heavier concentration) from Lowes. I also dumped in 6 gallons of bleach just to "kick start" the Cl until I could get the salt level back to range for the SWG to kick back in. From the moment the pool was opened till last night I ran the filter non stop. (so call it about 58 hours).

I'll provide a time line to make you follow easier:

Sun 10:30 am - Filter on
Sun 11:00 am - 1 Gallon MA
Sun 2:00 pm - 6 gallons Bleach
Mon 6:00 pm - FC = 3.5, pH = red line (meaning above 8.2)
Mon 6:00 pm - 200 lbs of salt to get SWG working
Tues 6:00 pm - FC = 4.0, pH = red line still, Alk = 90
Tues 6:00 pm - add 1 gallon MA - Run Dolphin to further help circulate
Tues 9:00 pm - FC = 4.0, pH = 7.5, Alk = 80, Calc = 350, CYA = 30 (low I know - I need to buy some)
Tues 9:30 pm - turned off pump and set it to run it's normal operation which will be from 10:00am - 6:00pm

Now, I have read "Pool School". I have read "Water Balance for SWG". I know I need to get the Alk a touch lower. And I have read "Lowering you Alk". But I have been adding gallons of MA for years. Day after day, week after week. Within a day of lowering pH it to 7.5 is will be back above 8.2 in 48 hours. And the Alk ALWAYS gravitates back to 90 ish. I guarantee you when I test again tonight the pH will be back to 8.0 ish and the Alk back to 90. How much acid do I need to add if I ever want to get this right? What can possibly cause the Alk to go up along with the pH? I get that the pH bounces because of the SWG, but why the Alk? Should I just CRUSH the pH down to sub 5.0 for a short period to kick this in the butt (I do have a bypass on my heater)?

My ultimate solution is to get an acid feeder - Whether I go the cheap DYI route posted here my mas985 (Homemade Acid OR Chlorine Injection System) or spend the coin to get a fully automated system has yet to be determined. For now I want to see if lowering the Alk to 60 will help with pH bounce. But I need help getting it there.

(Pool details in Sig)
 
What is the pH and TA of your fill water?

How many hours is the spa spilling over a day? Do you have any other features that aerate the water?

How many hours and output% is the SWG set for?

Is there an autofill?
 
+1 That spillover and SWG are rising your PH but that wont bring up ALK, test your fill water so we can see what it is and maybe help you get some sanity back :)

How much do you run the spillover per day? can you only run it 30 minutes just to keep it clean..
 
woodyp said:
My PH is much more stable around 60 or so. Your SWg and spill over spa are naturally driving your PH up.
Click to expand...

Yes I am well aware of this. SWG is the main culprit. I have done tests, turning each off independently in the past.

Texas Splash said:
Good morning Mike. To help us understand your history a bit more ..... what's the lowest you've ever taken your TA down to? Also, what is your fill water TA level?
Click to expand...

I can't say with certainty on either question. Will test fill water tonight. But quite honestly, other than the initial top off when I open pool, the amount of water I add is insignificant. I seem to always get lucky enough for a downpour to come just when I am getting low. (Typical Northeast summers)

Reddogdan said:
How are you testing?
Click to expand...

With this:

51I2AJcungL.jpg


ping said:
What is the pH and TA of your fill water?

6.2 and see above

How many hours is the spa spilling over a day? 8 when normal operation. Do you have any other features that aerate the water? No

How many hours and output% is the SWG set for? I vary depending on time of year, heat, pool usage, etc. But generally high. never less than 65% - sometimes 100%

Is there an autofill? No
Click to expand...

cowboycasey said:
How much do you run the spillover per day? can you only run it 30 minutes just to keep it clean..
Click to expand...

I run the spillover for the entire duration (8 hours). I can run it less. But like I mentioned above, the SWG is the main culprit based on my experiments in past. It's not a waterfall, per se. The spa height is the same as the pool height. So it just gentle trickles over the dam wall. Not a ton of aggitation.
 
ok, we have something to work with now, but I am still unsure how your TA is rising...

could you wipe the tip of the bottle before every drop doing the TA test, some times it makes smaller drops with static electricity. also, let the drip get big before it drops off the end. take your time. then post TA level

Once we know that we are going to drop your TA, take your PH to 7.2 then at 7.4 drop it again do this as many times till your TA drops to 70

We will see how fast your PH rises, if it rises in a day start over and take your TA to 60..

Just so you know, I have my TA at 50 and I can go about a month and not add any MA and when I do it is very little..

We will get you there :)
 
When trying to lower the TA, how important is it to get pH to exactly 7.2, back up to 7.4 and repeat? What if the pH got back to say 7.8 or 8.0 before I had a chance to hit it again? I mean this small range is very difficult to do considering how fast my pH bounces. That's why I asked in my first post if I should just try to completely obliterate the pH to a very low level.

And to be clear about the extremity of my situation..... During normal operation (Let's call normal = 8 hours pump time with SWG running at 75%) I need about 1/3 gallon MA every day to maintain a pH of 7.5. But to be honest I just don't have it in me to dose every day. So I will typically check every few days and dump an entire gallon in there in one shot.

Let's also point out that I have never had an Algae bloom. Never severe scale. Nobody's eyes burn after swimming. And water is always clear. Tell me again why I need to be so concerned with these readings?
 

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With regard to trying to lower TA, does it really matter if you let pH "bounce" to 7.4, 7.6 or 7.8 - (Or in my case 8.X +)? Isn't the idea to just keep adding acid until the TA is where you want it? And by the way, if I attempted to let my pH "stabilize" it is doing so WAY higher than any pool test reads.
 
You have to add MA to lower to 7.2, then aerate to drive the pH back up - mine gets aerated by the SWG.

Don't let it stabilize over 7.8. If you are hitting 8.0 or higher, (which mine does) you have to lower it back down.
 
Mike, You asked how to stop doing what you have been doing..

It is not hurting anything the way you are doing it other than you will be adding MA the same way you are doing now.. it seems like you are just dropping it enough to drop the PH but it barely touches the TA..

Like Robbie said and lowering TA says wait till PH rises to 7.6, it will just take longer, most of your PH rise and the fastest part of it is from 7.2 to 7.4 above that it will slow down

Lowering TA is done in a very deliberate way, usually over a weekend when you can drop, test, drop, test until you hit the TA your going for, then let your PH rise and see if it stops at 7.6/7.8 and then you are done, if it raises past that the next weekend drop TA to 60 and see what it does for the week.. :)
 
TY Cowboy. I guess said in another fashion and being that I am impatient. While I am not using my heater and I have the heater bypass on. And no one is swimming right now. Why not just blast the pH to an extremely acidic level. What's extremely? I don't know? I am hoping for some advice what you guys would be comfortable with? 6.0? 5.0? 4.0? I know it is going to be very short lived as the SWG gets it right back up there. But historically, only lowering the pH to the low 7's hasn't done squat for the TA. And I kid you not, I stock cases of this stuff at home and I go through it all throughout the season.
 
You put that pool at 4.0 and you are going to have issues most likely. pH is logarithmic, so each of those steps is a huge jump to the next. That would be like filling your pool with vinegar, which etches calcium carbonate.

You said you lower pH to 7.2 then let it rise to 7.4. That is not going to work. In my opinion, that's why it isn't getting lower.

I go through a gallon of MA per week.
 
RobbieH said:
You said you lower pH to 7.2 then let it rise to 7.4. That is not going to work. In my opinion, that's why it isn't getting lower.

I go through a gallon of MA per week.
Click to expand...

Pool school says down to 7.2 then up to 7.6 then repeat. Can you shoot me a number you think will work? We agree 4.0 is too low. I was trying to use extremes. But quite honestly, I am not too concerned about overshooting to the downside for a short amount of time. At the very least I will have less pumice stoning to do when I jump in.

And I consider a gallon of MA per week a lot. Not as bad as me, but still a lot. If someone told me a SWG would require $250 worth of MA a year, I may have reconsidered.
 
mikemass said:
Pool school says down to 7.2 then up to 7.6 then repeat. Can you shoot me a number you think will work? We agree 4.0 is too low. I was trying to use extremes. But quite honestly, I am not too concerned about overshooting to the downside for a short amount of time. At the very least I will have less pumice stoning to do when I jump in.

And I consider a gallon of MA per week a lot. Not as bad as me, but still a lot. If someone told me a SWG would require $250 worth of MA a year, I may have reconsidered.
Click to expand...

I'm working on getting my TA down to 70 to see what that does. If I still have big swings, I'm going to try 60. Once I find the most stable TA, I'm going back to 50ppm borates, as it helped me in the past. I have not re-added the borates since the replaster.

And, a gallon of MA per week is still cheaper than the amount of bleach I would have to buy.
 
This misunderstanding of TA has continued throughout the existence of TFP. You cannot lower TA with acid alone. aeration is part of the process and the ONLY way you can PERMANENTLY lower TA.

Here's the whole explanation quoted from Ben Powell's article that I have referred to many times...

[h=5]Step-by-step[/h]
  1. Test your ALK, and record it.
  2. Decide what your target ALK is.
    If your ALK is high, due to some past dosing error, target 120 ppm, unless you have some reason to go lower or higher. If you anticipate a continuing problem with high ALK, say due to high alkalinity fill water, target 100 ppm. (These are not magic numbers -- if you have a reason, and understand your options, other values can work as well or better!)
  3. Use small doses of acid
    to lower your pH to just ABOVE the lowest value on your testkit -- or 6.6, whichever is higher. Do NOT lower the pH to whatever the lowest value on your kit is! This is really important! In many cases, if you try to do so, you'll actually end up with a much lower pH, which can damage your pool. Instead, make sure that your pH is at least a little higher than the lowest pH value your kit shows. Also, do NOT try to lower your pH all at once; for all sorts of reasons, it's important to do it gradually!
  4. Begin aerating.
  5. Test your pH AND your alkalinity.
    Continue adding acid to MAINTAIN your low pH until your alkalinity reaches your target value. Once it does, continue aerating, but allow the pH to rise to the normal level. (If it doesn't rise on it's own after several days, you can add small amounts of borax -- NOT baking soda or soda ash -- to bring it up.)
  6. Once both pH and alkalinity are at target levels, stop aerating.
[h=5]How it works[/h](You don't have to know this part, to use the method.)
The portion of your TA that you want to lower is the CA -- carbonate alkalinity -- which is composed of the bicarbonates (-HCO3) and carbonates (=CO3) in your water.

These two ions are part of the carbonic system in water, which actually has FOUR components:

  • carbonates + bicarbonates + carbonic acid + free carbon dioxide, or
  • =CO3 + -HCO3 + H2CO3 + CO2
Each of these components can be converted into any of the others; what determines how much of each there is of each, is the pH. At pH levels above 11, all of the 'carbonics' present are in the form of carbonates: there is NO bicarbonate and NO carbonic acid. At pH levels below 4, all the 'carbonics' present are in the form of carbonic acid + carbon dioxide, with no carbonates and no bicarbonates. You can monkey around with the alkalinity test results, simply by changing the pH . . . but not matter what you do, once you restore the pH, all the original alkalinity will reappear . . . unless you get rid of some of it, somehow. and physically remove it from your pool.
There are two . . . and ONLY two . . . ways to do this.

  • You can precipitate it as scale or calcium carbonate (which is what happens when you add cal hypo, and get a white cloud), but this is very messy, or even damaging.
  • OR, you can turn it into carbon dioxide, and dump it into the air.
This process does the second: it converts some of your alkalinity into carbon dioxide, by lowering the pH, and gets it OUT of your pool, by aerating!
When you aerate your pool after a portion of your CA has been converted to carbonic acid (ie, by lowering the pH to 7.2 or lower) then gas laws come into effect. Contrary to what most people think, air has only TINY amounts of CO2. When you bubble air, with little CO2 through water with lots of CO2, the stuff follows the gas laws, and the CO2 levels try to equalize, so the concentration of CO2 in the bubbles is the same as the concentration in the water.
Now, you've actually done something; CO2 aka carbonic acid, has left the pool.
Because you've lost acid (carbonic acid, via carbon dioxide), the pH will rise, but this time, there's no carbonic acid to convert back to CA!
If your CA / TA level is not what you need to be, then you keep adding acid, so the pH will stay down:
. . . so the lost carbonic acid will keep being replaced with newly converted carbonic acid
. . . so the CO2 will keep gassing off
. . . so the CA will keep dropping.
When your CA gets where you want it, just stop adding acid, but keep aerating till the pH returns to the 'normal' level.
 

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