Unable to get pH where it should be

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jesses408

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Jul 26, 2016
57
Little Elm, TX
Over the past few days, the pH in my pool has gone from 7.4 to 7.6 to 8 (yesterday). This morning I measured the pH and got a reading of 8. Both the PoolMath and the treatment table of the Taylor test kit said to add 18oz of 20 baume Muriatic acid to the pool, which I did. This should have put the pH at 7.4-7.5. At 4pm I tested the pH again and got a reading of 7.8. I tested again at 10pm and got a reading of 8. I ran the test twice with different water samples just to make sure there was no mistake. The acid demand test is again calling for 18 oz. I don't understand why the acid I added earlier didn't correct the problem.

Also, I tested TA at 70 and have a CYA level of 35 and currently the FC is at 1. Page 14 of the taylor test kit directions say that I need to correct for cyanuric acid to measure total alkalinity using a formula ALKc = ALKta - (CYA * .33) which would result in a corrected TA of 58, which is too low according to the website recommendation of 70-90. Should I go by the corrected measurement or the original measurement?
 
You go by the original TA. Corrected TA is only used for calculating saturation indices like the CSI or LSI.

Alkalinity is alkalinity. Both the carbonate alkalinity and cyanurate alkalinity act as buffers in your pool water. For the purposes of pH stability it does not matter, to first order, where the buffering is coming from.

You could still lower your uncorrected TA to a minimum of 50ppm to see if that helps. My pool water pH is exceptionally stable when my TA is below 70ppm.
 
Do you run any aeration sources such as a spa spillway? Did you enter all of your parameters correctly into Pool Math? Are you sure your pool volume is correct?

Your FC is also very low for your CYA. Are you following TFP guidelines for maintaining a proper FC/CYA ratio?
 
It is also possible that it was higher than 8.0 since that is the top of the test scale. Keep testing and adding until I get gets back under 7.8. It is important to maintain PH between 7.2 and 7.8 at all times.
 
I do have a spa spillway. I entered all parameters correctly into pool math, and also independently calculated the amount of acid to add using the Taylor test kit acid demand test, which yielded the same answer. I don't know the exact pool volume - I'm estimating based on the square footage and average depth.

I put in chlorine after taking the test results. I put in concentrated bleach based on the poolmath calculation of 58 ounces to get me to 4ppm.
 
My suggestion is you should lower your TA to 60ppm or less and see how that affects your pH rise and acid demand. As I said, in my own pool when the TA rises above 70ppm, my acid demand starts to get noticeably higher. If you get down to 50ppm TA and your pH is still rising fast, then you can try adding 50ppm borates to act as an additional pH buffer.
 

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pookiesunshine said:
huh. i always thought a higher TA would create more of a buffer to minimize swings in pH.
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pooldv said:
No, higher TA will push PH up.
Click to expand...

This is often a confusing subject because most people don't realize that there are two distinct effects occurring here. First, TA is a pH buffer in water. The more TA you add, the more strongly buffered the water is. Carbonate alkalinity buffer capacity (i.e., how much the pH will change for a given amount of acid or base added) is strongest against pH falling since the pKa is below 7. However, because pools are an open water system (i.e., the water in the pool can exchange gases with the atmosphere), there is a second effect to adding TA - outgassing of carbon dioxide. Excess carbonate alkalinity over-carbonates pool relative to atmospheric levels of CO2 therefore there is always a driving force for CO2 to outgas from pool water; aeration from fountains, spillovers and such all increase the rate of outgassing. When CO2 leaves water, the bicarbonate ions in the water (the largest component of TA) try to restore the balance by consuming a proton (H+) and converting from dissolved bicarbonate into dissolved CO2. The process of this chemical reaction costumes a hydrogen ion and thus raises the pH.

So, both aspects are correct - carbonate alkalinity acts as both a buffer for pH AS WELL AS a source of rising pH itself.
 
This morning I put 32oz of muriatic acid into the pool. Tested it 1 hour later and got a pH of 7.2 with TA of 60. I also have the pump running at full power with the waterfall going to aerate the pool.

There are actually 3 sources of aeration - the spa spillover, a return on the top step that acts as a fountain, and the waterfall. The waterfall is the only thing that I can easily turn on/off. To stop or reduce the spa spillover, I'd have to take the spa return valve off of the computer control and adjust it manually. I don't see any way to stop or reduce the top-step return fountain since it's connected to all of the other returns and controlled by a single valve.

I'll test the PH again in a little while to see if it's drifting upwards from the aeration.
 
That's a lot of aeration.

Is the spa spill over controlled by water being returned to the spa jets or is there an extra return in the spa itself for use during POOL mode? My raised spa has 5 jets and a single return. When in POOL mode, water can be distributed to the three pool returns and the single spa return via an adjustable three way valve. This past winter I automated that valve so that I could schedule and control my spa spillover (previously, it ran all the time during POOL mode). I now only run my spillway 1 hour per day to reduce aeration. As well, my waterfall is on a separate pump so I only run that 30mins by 3X per day. Is the top step return fountain created by some sort of special return fitting? If so, you can usually unscrew return eyeballs and replace them with standard return fittings.

I'm sure all those water features look really nice but that much aeration is definitely driving your pH rise. Anything you can do to control it will be helpful in keeping a lid on your pH.
 
The spa has 5 side returns for when the system is in Spa Mode, and one floor return for when it's in Pool Mode. The valve that controls the floor return isn't independently automated - I'll post a picture. I can reduce the spillover by partially closing that return, but to completely stop the spillover I'd have to either close that return completely and stop water filtration in the spa, or leave it open and manually open the spa suction. Usually the spa suction is only on when it's in spa mode.

There may be a way to adjust the automation so that when in pool mode, the spa suction is slightly open, just enough that the water level in the spa doesn't decrease and the spillover is reduced. I have no idea how to do that - if it's possible.

The waterfall is normally off all the time. I don't usually even run it when I'm in the pool since it generates so much noise that I can't have a conversation while it's running. At time point I plan to find a way to fix it so that less water comes out of the waterfall when it's on.

The top step return looks like a normal return. It creates a fountain because there's only 2 inches of water up there.

JoyfulNoise said:
That's a lot of aeration.

Is the spa spill over controlled by water being returned to the spa jets or is there an extra return in the spa itself for use during POOL mode? My raised spa has 5 jets and a single return. When in POOL mode, water can be distributed to the three pool returns and the single spa return via an adjustable three way valve. This past winter I automated that valve so that I could schedule and control my spa spillover (previously, it ran all the time during POOL mode). I now only run my spillway 1 hour per day to reduce aeration. As well, my waterfall is on a separate pump so I only run that 30mins by 3X per day. Is the top step return fountain created by some sort of special return fitting? If so, you can usually unscrew return eyeballs and replace them with standard return fittings.

I'm sure all those water features look really nice but that much aeration is definitely driving your pH rise. Anything you can do to control it will be helpful in keeping a lid on your pH.
Click to expand...
 
Yup. That's what I thought. You can totally actuate your spillway. I recently (this past winter) upgraded mine with actuation.

See how your "FOUNTAIN" has a valve actuator on it. That's exactly what you need on the spa floor return. Those actuators have a a set of cams on the shaft which act as set points for motor travel. They come set at 180 degrees apart (full open one way or the other) but the cams can be adjusted so that one direction fully closes (feature off) and the other direction is only partially open (feature active). My spillway valve is either fully closed (no SPILLWAY) or set to 60/40 split between pool and spa (SPILLWAY active). I automate my SPILLWAY feature with a schedule of 1 hour per day. This assumes that your Jandy automation panel has another open 24VAC relay for an additional valve.

And I know - you were told by your PB that you absolutely had to run your spillway all the time or else the spa wouldn't get any chlorination and it would go green. Poppycock! I run my spa spillway 1 hour per day, it's 650 gallons, which means my pump turns over the spa several times. I also have a small bubble cover on the spa so that cuts down on FC loss from UV. The trick is to run your spa every couple of days for 30 mins to an hour just to make sure the pipes are seeing fresh water.

My suggestion would be to automate your spillway or, if you were limited in the number of valve relays you had, I would switch the automation from the waterfall to the spillway. It sounds like your waterfall doesn't get much use so that valve actuator is idle all the time.
 
jesses408 said:
Turning on the waterfall also puts the pump into its highest speed. I'll have to change that if I move the actuator to the spa return. I'm not sure how to adjust those parts of the programming
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If it's anything like the other manufacturers (Hayward and Pentair), the programming is usually pretty simple. We have plenty of Jandy owners on this forum, I'm sure one of them could easily navigate you through the programming. The hardest part would be switching the actuator over to the other valve and opening up the actuator to adjust the cams. But thats nothing more than a few turns of a screwdriver....up to you of course. Aeration is your primary problem so you need to bring that under control as best you can.
 
Here's how my pH levels have been the past few days-

DateTimeFCpHADTA
7/28/20161:00 PM282
7/28/20164:00 PM7.8
7/28/201610:00 PM1870
7/29/20169:37 AM3.57.81
7/29/201612:17 PM7.260
7/29/20164:08 PM7.460
7/29/20169:36 PM27.6160
7/29/201610:51 PM4.57.260
7/30/20161:42 PM7.660

The drops in pH are when I added muriatic acid. The first 2 drops, I added 18 oz. The next 2 drops, I added 26oz.
I think the TA at this point is really 55 but I can't measure half drops. Should I


  1. Keep trying to get the TA lower (to 50?)
  2. Add borax
  3. Remove the top step return fitting and replace it with something that doesn't aerate the water

Here's the main source of aeration - the return on the top step-
View attachment 52737

View attachment 52736
 

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