Desperately Seeking Help with Ammonia and CYA

[jimarbuckle]

Today’s Test Results:

Pool Store
FC – 5+
TC – 5+
pH – 7.8
TA – 160
CH – 200
CYA -100

Me, using DPD Deluxe Test Kit, 3 hours later
FC – 2
TC – 5+
pH – 8.0
TA – 180
CH – 210
CYA -65
Salt - 5,000 according to my SWG
Ammonia (2-part sodium salicylate/sodium hydroxide test) – 8+

The SWG manufacturer says the optimal chemistry for the SWG is:
FC – 1-3
pH – 7.2 – 7.8
TA – 100-200
CH – 200 – 300
CYA – 30 – 60
Salt - 3,000 to 5,000, 6,000 max.

For the past two seasons, I have had huge problems getting any FC in my pool. The pool would eat through tablets voraciously, and constant shocking with 73% calcium hypochlorite would barely bump my FC, which consistently hovered at about zero (as measured by the local pool store and by me using test strips purchased at Lowe’s). The pool would get hazy and I’d shock with a few bags of calcium hypochlorite, the pool would clear some and then in a few days the hazy/shock cycle would start anew. In short, I foolishly kept asking the local pool store for help, and it has now dawned on me after finding this forum that the ladies there, while nice, are blissfully ignorant of pool chemistry. Doh!!

I use a mesh safety cover during the winter, which I removed on May 1. I vacuumed the silt and debris (fewer earthworms this year than normal!), back-washed, and shocked with two lbs. of 73% calcium hypochlorite, and added a quart of non-copper, non-foaming algaecide. The pool cleared fairly well in a couple of days, and the TC chlorine stayed high, but the FC dropped to about zero. I did not have the SWG turned on for the first week. The water stopped clearing at about slightly hazy, so I turned on the SWG and hit the super chlorinate button (100% for 24 hours). The pool cleared some more, to the point that it was close to completely clear, but then hazed up within a couple of days after I set the SWG to 60%, running 16 hrs. per day. This time the haze had a slightly green tint to it. Last night I turned off the SWG and shocked again with 2 lbs. of 73% calcium hypochlorite. It cleared up very nicely over night and looks pretty good, but after having read some of the threads in the forums here I came across 1. CYA and “chlorine block,” and 2. the problems with ammonia. A light went off over my head--albeit a dim one. So my questions are:

• What do I do about the ammonia?
• If the answer is massive additions of bleach, should I worry about the copper heat exchanger in my pool heater getting corroded? I do not have a bypass arrangement for the heater.
• I’ve read on the boards that to shock you need to get the FC to 13, but how do you test that high? My test kit only goes to five. Even Spinal Tap’s test kit only goes to 11!
• Should I drain ~50% of the water out of the pool to get the CYA down?

I appreciate any help you can offer, and thanks.

 

[257WbyMag]

• What do I do about the ammonia?
You are going to need to shock your pool until the ammonia is gone and your FC holds overnight.

• If the answer is massive additions of bleach, should I worry about the copper heat exchanger in my pool heater getting corroded? I do not have a bypass arrangement for the heater.
Shocking with bleach will not cause problems with your heat exchanger. What will though is your pH which is 8.0 already. pH should be around 7.2 before you shock. Now, what is unclear is what the true value of your FC is because if you FC is higher than 10 ppm right now, your pH may be reading falsely high. We really need to know what your true FC is at this moment.

• I’ve read on the boards that to shock you need to get the FC to 13, but how do you test that high? My test kit only goes to five. Even Spinal Tap’s test kit only goes to 11!
Man, I love that movie! Anyhoo, to test that high, you need a FAS-DPD chlorine test. You can get this from TF Test Kits (see link in my sig). This will allow you to test as high as you need to.

• Should I drain ~50% of the water out of the pool to get the CYA down?
You can, but you probably don't need to. I tend to believe your CYA reading over the pool store reading. You said 65 ppm on the CYA, or I'm guessing, somewhere between 60 and 70, and that should be fine, considering that you are running with a SWCG. Your shock level is an FC of 28.

I appreciate any help you can offer, and thanks.

Edited one time for content regarding pH and high FC.

 

[svenpup]

I’ve read on the boards that to shock you need to get the FC to 13, but how do you test that high? My test kit only goes to five. Even Spinal Tap’s test kit only goes to 11!

Your shock level (as well as your normal target level) are determined by your CYA. At CYA = 65 your shock level is 19.

 

[Butterfly]

We have some variance on the shock level, but rounding up the CYA to 70 and using the Chlorine/CYA Chart, the shock level would be about 28.

The Chlorine/CYA Chart shock level (link in my sig) is more aggressive than Jason's Pool Calculator shock level (link also in my sig).

Dealing with ammonia, I would choose the more aggressive shock level.

Welcome to the forum

 

[jimarbuckle]

Thank you all for the help.

6:10 PM EDT: I've just checked the FC, and it looks to be 1.0 or thereabouts, with the TC way above 5.0. This means that FC has dropped from 5+ to 1.0 since about lunchtime today. I have added muriatic acid this afternoon and have the pH down to about 7.6, and will adjust again to try and get it to the 7.2 area.

Thanks for the welcome. I think I've learned more today reading this forum than in the last 10 years of having this pool.

 

[poolgirl22]

I try to welcome fellow hoosiers!

Welcome to TFP!!!

You are in good hands here...

 

[frustratedpoolmom]

Did you add any other products from the pool store to try to clear this pool, like a "yellow-out" product...?

 

[jimarbuckle]

Did you add any other products from the pool store to try to clear this pool, like a "yellow-out" product...?

I did not. The only chemicals that have gone into the pool since opening this year are:
• 73% calcium hypochlorite
• Salt
• Algaecide
• Flocculent (the blue stuff)

Thanks for the help!!

 

[frustratedpoolmom]

Its just odd to have ammonia present but still have CYA left. Usually when the ammonia is present the CYA reading is non-existent. I was trying to pinpoint some other source.
Did you add more CYA when you opened?

 

[257WbyMag]

Did you add more CYA when you opened?

I was kinda wondering that too. Or perhaps fertilizer contamination.

 

[chem geek]

If the FC got to zero at some point, then bacteria can grow and convert CYA into ammonia (this is explained technically here). Such bacteria do not have to convert all of the CYA; they may stop growing because they run out of other nutrients such as phosphates or they just self-limit for whatever (lucky in this case) reason. At any rate, the way to clear the pool of ammonia is to add a lot of chlorine and to do so frequently. Chlorinating liquid or bleach are best for this purpose unless one wanted to intentionally increase the CH level in which case Cal-Hypo could be used where for every 10 ppm FC added by Cal-Hypo, it also increases CH by at least 7 ppm.

You can see a summary of my own personal experience clearing a pool of ammonia in this post where you can see that the key is to keep adding chlorine until you start to register an FC reading and then keep adding more until it gets to a higher level. In your case with CYA still in the water, you want to get the FC up to shock level, or around 25 ppm FC or so. Notice how I had to add chlorine very frequently at first and that it would not register as FC but initially as CC. Eventually, the FC starts to register, though it doesn't hold. At some point, the FC both registers and holds. After that, it was more like a normal clearing of cloudiness from algae in the pool as I probably had both, or the cloudiness could have been dead bacteria -- either way, traditional shock levels cleared it.

Theoretically, 8 ppm ammonia would take at least 60 ppm FC cumulatively added to clear and could take a lot more since the bacteria can convert some of the CYA into intermediate products that aren't yet at ammonia so don't register in either the CYA test nor the ammonia test. Just keep adding chlorine until the FC starts to register. If you want to get an estimate of how much it will take, you can do a bucket test using pool water and knowing that 1/4 teaspoon of 6% bleach in 2 gallons is 10 ppm FC.

To prevent this problem in the future, make sure you close the pool only after the water gets cooler, below 50ºF, and shock it with chlorine and optionally use PolyQuat 60 as well. If you can check the water during the winter and notice the FC getting low, then add more chlorine and mix manually with a brush. If your pool gets a layer of ice on the top, then this isn't practical. During spring, open the pool early, before the water gets above 50ºF, and add chlorine to get a measurable FC. There are other more expensive ways to take the edge off of bacteria growth during the winter, but having at least some chlorine in the pool is the cheapest way to deal with this and the chlorine usually lasts a long time when the water is cold. It is possible that the use of 50 ppm Borates may prevent or slow down this problem, but that's just speculative at this point -- it does seem to take the edge off of algae growth, but I'm not so sure about bacterial growth.

Richard

 

[jimarbuckle]

Did you add more CYA when you opened?

I did not add any CYA when we opened the pool. Last year's number for CYA were above 125 towards the end of the year, presumably from using tablets to chlorinate. Lowering the water level for closing and and then again this spring for all the snow/rain that went in, may account for some of the loss over the winter. Also, with the mesh cover I do get a copious amount of earth worms and some leaf debris that gets into the pool in the fall and spring (presumably the earthworms aren't burrowing out of frozen ground). Perhaps their decomposition adds to the ammonia levels? As for fertilizer, possibly, but I have been very careful with fertilizer around the pool for the past few years. I asked the pool store to check for nitrates and the test was negative. Phosphates are <100.

Also, I'm not getting no FC from shocking, as the two pounds of 73% calcium hypochlorite I added Tuesday night did take the FC up substantially, but it dropped back down to negligible levels over the course of 36 hours. I don't know what that means in light of Richard's comments.

I will certainly try the bucket test, and then begin shocking once the weekend is over and the kids are done with the pool. I'm assuming that once I start this regimen, it is going to be at least a week or so before anyone can get in the pool, is that correct?

Again, thank you all for all the help.

 

[frustratedpoolmom]

That would be an easy estimate. Good luck!

 

[257WbyMag]

Jim,

It sounds like you were in the process of losing your CYA when you caught the ammonia problem. Most of the time, people with ammonia in their pools have already lost their CYA completely (and can't understand why).

I assure you that you are getting FC from shocking, it's just being used up very quickly. What chem geek was saying is that you would likely need a cumulative dose of around 60 ppm to clear the amount of ammonia in your pool that the test indicated you have. It has been our experience on this forum that those with ammonia typically require massive amounts of chlorine to clear the ammonia. chem geek was painting that picture for you so that you could be prepared and understand a little more about this particular situation.

You mentioned that you would try the bucket test. Are you thinking that you might have a leak somewhere because I didn't see it mentioned in the thread?

 

[jimarbuckle]

Thanks. I'll check CYA again and see if it is decreasing. I think I'm prepared. It's my wife who is unconvinced, "The pool looks great, why are you trying to mess it all up? What do you mean the kids won't be able to use if for a week!?" And so on. I went out last night and bought 52ppm worth of bleach--would have gotten more but that was all Wal-Mart had.

I'm uncertain what you mean by a leak. I was referring to Richard's comment about adding bleach by the 1/4 tsp. to two gallons of pool water in a bucket to test the PPM of FC that will be needed. Is there another kind of bucket test? Or did I misunderstand what he was suggesting?

 

[257WbyMag]

I'm uncertain what you mean by a leak. I was referring to Richard's comment about adding bleach by the 1/4 tsp. to two gallons of pool water in a bucket to test the PPM of FC that will be needed. Is there another kind of bucket test? Or did I misunderstand what he was suggesting?

Oh, okay. I missed that part.

Yes, when we hear of someone doing the "bucket test", we usually think of that as a way to check a pool for leaks. I'm glad to hear that you are not having that problem.

 

[anonapersona]

Are the kids peeing in the pool?

 

[chem geek]

Kids peeing in the pool would not generate 8+ ppm ammonia in 23,000 gallons. The composition of urine is 10,240 mg/L urea, 560 mg/L ammonia plus other compounds. Though the urea combines with chlorine and can show up as Combined Chlorine (CC), it will not show up as ammonia in an ammonia test. 8 ppm is 8 mg/L and 23,000 gallons is 87,000 liters so that would be 696,000 mg of ammonia (in Nitrogen units). It would take over 1240 liters of urine to produce this level of ammonia.

 

[Ohm_Boy]

That's a lot of pee.

 

[jimarbuckle]

Are the kids peeing in the pool?

Well, of course my kids aren't, but I can't vouch for all of their friends! Seriously, I do doubt it.