Crazy ph

[christianday]

I will post a pic when I get home. Nobody is adding baking soda. I accidentally added about a third of a jar of ph up by accident some weeks back but that effect should be gone.

The pool builder said that the aeration is what gives the swim jets their power so that won't work. I think Chem geek may be right but I have to find out what equipment I have and taking photos and writing down numbers didn't tell me what these were oddly. The serial number to the pump brought up filter cartridges. I need the builder to get me this info.

The pH is above 8.2 again though it's not climbing at .3 anymore. It's back to around .1 per day. It's possible that my TA needs to be at 40 or something

Nothing is visibly wrong with the plaster. It looks and feels great. No scaling.

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P.s. My fill water has a TA of 140, pH of way above 8.2 and CH of 180. I'm afraid to take a shower in it. Lol

 

[chem geek]

Yeah, New Orleans intentionally raises the pH along with the higher TA and CH in order to saturate the water with calcium carbonate in an attempt to prevent corrosion in their cast iron pipes, but most utilities now use specific corrosion inhibitors instead since it is more reliable.

 

[christianday]

Not surprising that New Orleans does crazy stuff or the water.

I still have to take a video of the pool. Gonna YouTube it.

The sun is very bright over this pool and the heat and humidity here are crazy. That may also have effect. I'm looking into sense and dispense. I just won't use the ORP. I like the larger tank and the fact that it is another Hayward product and integrates with the Omnilogic.

 

[christianday]

Here is a video of the four swim jets for our 10k gallon pool. They are turned on in pairs and each pairs is powered by a pump. I am waiting to hear from the PB on what power the pumps are but you can see here that they aren't exactly wimpy.

Pool swim jets - YouTube

Does looking at the pool give anyone ideas about why the pH would be climbing so quickly?

Again, sunlight is hard all day on the pool, the heat is crazy with the pool water at 88 degrees Fahrenheit with the heater set to 84 degrees.

The plaster is just about three and a half months old so I was wrong about that being five months so maybe that's the calcium shifts.

I ordred the magnetic stirrer and borate strips and water testing vials and tubes from TFTestkits.net to supplement the TF100 but I'm convince this is spiking.

Since it's been a few days and the pH is now over 8.2 and since it looks to be far over 8.2, I added an entire gallon of muriatic acid and have the jets aerating now. Whatever it brings the TA to, it is what it is, I have to try to fight this pH spiking. As it is, any pool professional would have to come three times a week to make the pools swimmable so I need to get one of those sense and dispense machines. In the long run, it will cost less than the pool professional.

Here's the problem though. The whole point of the boric acid was to stabilize the pH and it isn't doing that, perhaps it's best to get rid of the boric acid so I don't have to add quite so much muriatic acid to stabilize the pH? I'm going to call one of those services that does the reverse osmosis to the water. I just can't see getting a dispenser that's going to have to work that much harder because of the borates in the water.

 

[christianday]

So about an hour into the aeration after adding one gallon of muriatic acid, the TA is 60 and the pH is 7.4. I'm shocked that's all the MA brought it down to. That must mean the pH was up around 8.5 according to the pool calculator.

Any ideas?

 

[YippeeSkippy]

Yeah...turn the jets off

 

[christianday]

YippeeSkippy: did you see the video? LOL

I have them on now just to get the TA down cuz I added another half gallon of MA after adding a gallon earlier because I want to get the TA to 40 or 50 to see if it will hold better then.

What really amazes me is that the pH is so much harder to lower but raises as fast, if not faster, than it ever did with the borates there.

 

[christianday]

I'm currently at 7.2 and TA 60 (which seems to be leveling). I want to get the TA to 50 so I'm still aerating. Here's the current chemical journey marked out:

 

[christianday]

I just added the remaining half gallon to try to get the TA to 50 or below. The pH was already at 7.2 so who knows how that's going to play but I'm ready to try anything at this point. That's two gallons today. I've got it aerating so it will probably get the pH up somewhat. Definitely going to be using the jets at a minimum until we get an acid dispenser since two gallons of MA in one day is a bit crazy.

 

[chem geek]

If you added a gallon of full-strength Muriatic Acid to the pool and ended up with a TA of 60, that means it was 110 ppm before you added the acid. It's hard to know what the pH originally was due to carbon dioxide outgassing or plaster curing or other effects but if those effects were not there then the pH started at 8.6 to get to 7.4 (with the 50 ppm Borates in place). And yes, it takes more acid to lower the pH -- that's the whole idea behind buffering the pH. It should prevent the pH from rising as quickly as well, but for whatever reason it hasn't.

You need to be careful about adding so much Muriatic Acid when the TA is low. Adding a half gallon would lower the TA by another 25 ppm to 35 ppm so your getting it pretty low. If your pH rises above 7.7, then the pH rise is most certainly not (only) from carbon dioxide outgassing, but I think we already know that given the rise in CH and TA you also see.

I think you are getting dangerously low in your calcite saturation index so while experimenting with low TA is one thing, you can't keep it that low without having the CH and pH target be higher, but it isn't worth doing that if the plaster is going to keep releasing chemicals (such as calcium hydroxide) that increase CH and TA.

Also, don't forget to add the acid slowly with the circulation on over a return flow and to lightly brush the side and bottom of the pool where you add the acid. If you add it quickly in one place, it can pool and dissolve the calcium carbonate in plaster which is not only bad for the plaster, but will have the CH, TA and pH rise from the dissolved calcium carbonate.

 

[AimeeH]

YippeeSkippy: did you see the video? LOL

I have them on now just to get the TA down cuz I added another half gallon of MA after adding a gallon earlier because I want to get the TA to 40 or 50 to see if it will hold better then.

What really amazes me is that the pH is so much harder to lower but raises as fast, if not faster, than it ever did with the borates there.

Aerating won't bring your TA down.

 

[christianday]

chem geek: I only add the acid with all four swim jets on, since that pushes everything around and I add relatively slowly far as I can tell.

The TA is currently at about 45 and the pH is at 7.2. I'm not going to aerate anymore till I get up tomorrow because the pH rose from roughly 6.8 (or even lower) to 7.2 in a little over two hours of aeration. That's like .2 per hour at least so I don't want to chance that same rate happening while I'm asleep. I'll end up waking up to 8.8pH. I doubt it actually works that way in but I don't want to take a chance.

I think the CH is probably still at 450. I will check tomorrow. I figure the 7.2 pH can stay there till I'm awake. At least I hope.

 

[christianday]

So after running two of the four swim jets for eight hours, the pH is up to 7.5 but the TA has also risen from 45 to 60.

Here's a thought. I wonder if the mega-dosing of acid is causing the relatively new plaster to add stuff to the water causing TA rise.

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[chem geek]

It's not the acid dosing itself that would necessarily be the issue (if it were well mixed) but the low pH and now low TA resulting from that which could exacerbate the problem. If the acid didn't mix well and pooled anywhere for locally low pH, then that could dissolve calcium carbonate and unplug the plaster to release calcium hydroxide, both of which would raise TA and pH. If the pH, TA, and CH combination were low so that the calcite saturation index were low, then that could also dissolve calcium carbonate, unplug plaster, etc.

However, since in your pool it is the swim jets that are the unusual element, it would be best to test for stability of the water with them turned off. If the TA is at 40-50 ppm and the pH at 7.8 and the swim jets are off, then if the CH and TA don't rise and the pH is fairly stable then the issue is more directly related to the swim jets, and not just aeration driving carbon dioxide out of the water but something about them making the plaster be more unstable. What is most strange about your situation is that normally if the CH, TA, and pH were all rising and you got your calcite saturation index high as a result, that should have produced calcium carbonate in the plaster to seal it off and could produce either visible scaling on the plaster, cloudiness in the pool water, and/or scaling in the SWCG cell. You've never mentioned seeing any scaling or cloudiness no matter how high your TA and pH got.

It may be that the use of swim jets has consistently stripped away calcium carbonate from the plaster. While I could understand this happening in very new plaster, it's surprising this could still be happening several months after the pool was completed. Plaster has been known to have CH, TA and especially pH rise for up to a year, but the most is usually in the first week and then first month. Maybe you started using your swim jets right away and the plaster never really got properly sealed with calcium carbonate as a result. If you were willing to stop using your swim jets for some number of days, we can see if maybe we can seal the plaster with calcium carbonate to stabilize it, basically doing something like a bicarbonate startup.

Have you felt the sides and bottom of your pool to see if the plaster still feels smooth or if it is more rough or if it has tiny holes?

 

[christianday]

I don't have a test for calcium saturation index.

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The plaster feels pretty smooth with no holes. It's a light grey so it's always been a little streaky but it's entirely possible that it's still seeping stuff into the pool due to the jets or acid. I did use an awful lot of acid at once.

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My filter used to be 12 hrs per day and now it's 20.

 

[christianday]

Doing full tests now but did pH first and, 7.5 hours later with no jets, the pH has gone from 7.5 to roughly 7.8 so that's a .3 increase in 7.5 hours. And from the looks of the color, it feels slightly above 7.8 so it's climbing. There has to be a reason for this after two gallon of muriatic acid in a pool with between 30ppm and 50ppm borates (I can't tell because those strips aren't all that easy to use). Will post complete test as soon as I'm finished but this is insane.

 

[christianday]

Here's today's numbers.

 

[swoopman]

The calcium saturation index (CSI) calculation is right under Temp on the Pool Math page. You input your current levels on the page and pool math calculates the CSI for you.

 

[chem geek]

So a CH of 425 is roughly the same (within test error) of the 450 ppm you measured before so the CH doesn't seem to be rising, at least not a lot, BUT it doesn't take much to have the pH rise with the plaster still dissolving.

With your numbers, it would take 16 ppm of calcium carbonate (1.34 pounds of calcium carbonate) to go from pH 7.5 to 7.8 but should have the CH and TA rise by 16 ppm. However, if it is calcium hydroxide being released, then it would take only 8 ppm so you may not measure a CH and TA rise of 8 ppm (the TA would be within test error).

See what happens now that it's pH 7.8. The calcite saturation index would be around -0.2 so still not saturating the water, but with the water still it should convert calcium hydroxide to calcium carbonate more in place in the area of the plaster where the pH would be rising. Let's see if that happens and the pH rise slows down.

 

[christianday]

I'm leaving the jets off until this whole process is solved, which sucks because even with the filter running 20 hours per day, there's a lot of tiny bugs that don't seem to be skimming out with the pole skimmer and the jets help that too. Of course the rain made the pool a little fuller than normal and the built in skimmers don't work as well in those instances.

The TA is at least holding for the past couple days at least. I'm not adding any acid again until the pool builder gets his sample to a pool store. It may not help but at least we'll get a more comprehensive view of what's in the water.