Chemical mystery

[DougFL]

Hey everyone, my name is Doug from Pensacola, FL. I am a newer pool owner at just 14 months of ownership. I am dealing with some chemical quandaries in my pool as I completely bungled my pool water from a complete lack of any research whatsoever into balancing pool chemicals. I have since read the Pool School articles and downloaded the PoolMath app but still have some issues that I cannot find answers for. Below are my levels as of today (sunny, 90 degrees, 80% humidity) -

FC - 23.5
TA - 0
Ph - level too low to measure but presumably low 6's
CYA - Too high to measure but I am estimating around 210 which is why FC is high based on recommendations from PoolMath

After 14 months of reckless puck and shock usage and never measuring levels we found out our CYA was very high from Leslie's since we had some light algae appearing but with very clear water. I realized out after just a few visits that major pool chains are about as helpful as a screen door on a submarine so after some research I was lucky enough to find TFP. I purchased the Taylor K-2006C kit and began testing my levels and adjusting in accordance with the PoolMath app (I now believe my CYA may have been 400+ prior to draining and refilling more than half our pool over the course of 2 weeks). My initial results were the same as above except my FC was .5 and PoolMath said to add roughly 512 ounces of liquid chlorine, which I did, and that brought my level up to 23.5 which was my second reading, the first was 18. I took the first reading after an hour with the pump on high so I am confused why the FC jumped up 5.5 ppm in 24 hours, perhaps operator error with the testing kit? My second issue is that PoolMath suggested I add 18 lbs of baking soda as my TA level measured at 0. I first added 8.5 lbs and tested and then 5.5 more lbs and tested but both times my reading was 0. The water sample never turned green when adding the reagent and went straight to red.

I know the first course of action should be to drain more of my pool to get the CYA to optimal levels but I am perplexed as to why my TA is still at zero, what my true CYA level is and if there is a way to find out and should I address Ph before addressing TA?

Thank you for taking the time to read this and hopefully it is cohesive enough but for anyone willing to respond please let me know if there are any questions about my situation so I can hopefully get some clarity.

Thank you,

Doug

 

[reggiehammond]

With CYA far out of whack, it’d be wise to just move to water exchange. You’re going to have to do it, no matter what, so let’s not worry too much now. It’d be helpful to know true CYA content to inform how far to drain - but it’s going to be most of it if what you portray is true.

Draining - Further Reading

www.troublefreepool.com

 

[DrewLG]

The water sample never turned green when adding the reagent and went straight to red.

I know the first course of action should be to drain more of my pool to get the CYA to optimal levels but I am perplexed as to why my TA is still at zero, what my true CYA level is and if there is a way to find out and should I address Ph before addressing TA?

You have extremely low pH and zero TA. You should fix them both, which you can do simultaneously by adding sodium carbonate (aka soda ash, aka washing soda) -- note that this is not the same as sodium bicarbonate aka baking soda.

But a water exchange will also move TA and pH in the right direction, so if you're exchanging water to fix CYA anyway (and can do it soon), do that first.

 

[DougFL]

You have extremely low pH and zero TA. You should fix them both, which you can do simultaneously by adding sodium carbonate (aka soda ash, aka washing soda) -- note that this is not the same as sodium bicarbonate aka baking soda.

But a water exchange will also move TA and pH in the right direction, so if you're exchanging water to fix CYA anyway (and can do it soon), do that first.

Thank you for the reply, I will start draining as soon as the storms pass this weekend. Regarding the TA, do you have any idea why the TA did not move with 13.5 lbs of baking soda? The Effects of Adding in PoolMath said it should have brought my TA to 55 ppm so I am confused why it has remained at 0.

Thank you - Doug

 

[mknauss]

Regarding the TA, do you have any idea why the TA did not move with 13.5 lbs of baking soda?

TA can be negative. You cannot measure that with the tests we use.

 

[JamesW]

When the TA is initially red, the TA is 0 or negative.

To calculate the actual TA, use R-0006 base demand to titrate from red to green and then multiply the result by 6.3 to see how negative the TA is.

 

[DougFL]

When the TA is initially red, the TA is 0 or negative.

To calculate the actual TA, use R-0006 base demand to titrate from red to green and then multiply the result by 6.3 to see how negative the TA is.

Thank you for that. I just did that test and it took 2 drops to go to green so that looks like negative 12.6, though I cannot log negative numbers in the poolmath app to get a recommendation on how much baking soda to add. That brings me to 2 more questions -
1. The Taylor test kit guidebook says that high chlorine levels can throw off TA readings and with my FC being 23.5 to accommodate my sky high CYA reading of roughly 210, can that give a false TA reading?

2. If I added enough baking soda to raise my TA by 55pm (according to PoolMath) would that mean my TA was previously negative 67.6 prior to adding the baking soda? I am in the midst of a slow drain and refill to lower CYA levels and won't be adding anything until that is under control.

Thanks again - Doug

 

[JamesW]

If I added enough baking soda to raise my TA by 55pm (according to PoolMath) would that mean my TA was previously negative 67.6 prior to adding the baking soda?

Yes.

The pH would have been about 2.87

pH = -log_10(0.00002TA).

-log_10(0.00002(67.6)) - Wolfram|Alpha

Wolfram|Alpha brings expert-level knowledge and capabilities to the broadest possible range of people—spanning all professions and education levels.

www.wolframalpha.com

y = -log_10(0.00002 x + 0.0000316228) and y = -log_10(0.00002x) | x = -2 to 100 - Wolfram|Alpha

Wolfram|Alpha brings expert-level knowledge and capabilities to the broadest possible range of people—spanning all professions and education levels.

www.wolframalpha.com

y = -log_10(0.00002 x + 0.0000316228) and y = -log_10(0.00002x) | x = -2 to 2 - Wolfram|Alpha

Wolfram|Alpha brings expert-level knowledge and capabilities to the broadest possible range of people—spanning all professions and education levels.

www.wolframalpha.com

y = -log_10(0.00002 x + 0.0000316228) and y = -log_10(0.00002x) | x = -2 to 0 - Wolfram|Alpha

Wolfram|Alpha brings expert-level knowledge and capabilities to the broadest possible range of people—spanning all professions and education levels.

www.wolframalpha.com

The Taylor test kit guidebook says that high chlorine levels can throw off TA readings and with my FC being 23.5 to accommodate my sky high CYA reading of roughly 210, can that give a false TA reading?

The reading should be ok.

I just did that test and it took 2 drops to go to green so that looks like negative 12.6, though I cannot log negative numbers in the poolmath app to get a recommendation on how much baking soda to add.

I would add enough baking soda to raise the TA by about 80 ppm to get the pH into a safe range.

 

[JamesW]

20 lb baking soda should be 80 ppm, which should result in 80 - 12.6 = 67.4 ppm TA.

 

[DougFL]

20 lb baking soda should be 80 ppm, which should result in 80 - 12.6 = 67.4 ppm TA.

Thank you James, I truly appreciate you taking the time to respond to me. I had no idea what a disaster my chemicals were but am happy to have found TFP to get this in order.

 

[DougFL]

20 lb baking soda should be 80 ppm, which should result in 80 - 12.6 = 67.4 ppm TA.

TA can be negative. You cannot measure that with the tests we use.

Hi again,

I am in the process of draining and refilling my pool as I did a CYA dilution test and it read about 160ppm and this is after draining and refilling 3/4 of the pool). I live near Pensacola in a special hazard flood zone where my water table is fairly high which is why I have an above ground pool and not IG. I could not find any threads regarding the simultaneous drain and refill process for an above ground pool. I have seen other replies from experts stating that putting the refill hose at the bottom with the colder heavier water while draining warmer water from the top is the appropriate process but does this same process apply to an above ground pool with equal depths? Another noteworthy thing about our tap water is that where I live in NW Florida, the water pipes are only about 12 inches below the surface so our tap water comes out warm like the weather. I have not measured exact temperature but it is definitely not cold.

Thanks in advance - Doug

 

[mknauss]

You can drain down to leaving 12 inches of water in the pool and then refill. Best if you be sure no high wind storms are likely when the pool is empty. Watch it once you get to 24 inches left and if you see a shift of the liner of any kind, stop and refill.

 

[DougFL]

You can drain down to leaving 12 inches of water in the pool and then refill. Best if you be sure no high wind storms are likely when the pool is empty. Watch it once you get to 24 inches left and if you see a shift of the liner of any kind, stop and refill.

Thank you, Marty. I appreciate your response.

 

[DougFL]

Hey everyone, I am having an issue with what I suspect is mustard algae. This is the 2nd time, maybe 3rd, that I have had a return of this invader. Both times I have followed SLAM procedure and moved on to the Mustard SLAM FC levels. I am diligent about doing my chemical testing and adding liquid chlorine when needed and pass all tests but a month later it becomes very visible. This time is odd because after passing the initial SLAM and moving on to Mustard SLAM I am still seeing light green/yellow clouds when I brush the bottom of the pool, and I also lost 2.5PPM of FC overnight when I had passed 2 OCLT during the initial SLAM as well as. This FC overnight loss is in addition to 5 PPM loss within the first 8 hours of my Mustard SLAM. My question is how can my readings be showing this kind loss when it did not during the regular SLAM? Are readings skewed at high chlorine levels? And what should I do as my 24 hours has expired on my Mustard SLAM?

Thank you in advance - Doug

 

[DougFL]

Test Results:
FC - 33.5
TA - 70
CYA - 55
Calcium - 90
PH - 7.7

 

[mknauss]

moving on to Mustard SLAM I am still seeing light green/yellow clouds when I brush the bottom of the pool,

You did not finish the original SLAM. All three criteria need to be passed.

You will have significant testing error at MA SLAM levels.

 

[DougFL]

Hi Marty and thank you for the response. I can't believe I missed the algae clouds in my rush to get to mustard SLAM. At this point will I need to restart the initial SLAM process or is there a way to defeat the MA with these high chlorine levels?

 

[mknauss]

You can defeat it, but you will have trouble testing. Less chlorine and easier testing to let the FC come back to SLAM and finish that.

 

[mknauss]

You have an above ground pool. Be sure there are not folds, creases, stairs, etc that can hide algae.

 

[DougFL]

Thank you for that. I removed the stairs and cleaned them by hand with a diluted chlorine solution but there are so many crevices It is hard to imagine I was able to get every bit of it. I do have some small creases in my liner but I feel like I am pretty good at scrubbing those.