TF100 Chlorine Confusion

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piku

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LifeTime Supporter
Mar 12, 2008
259
Hatfield, PA
Hey guys,

Bought the TF100 chlorine test only (since I have taylor K-2005C) and I am doing a bucket test right now to see how much chlorine my water is going to consume. We suspect an ammonia or fertilizer problem in general. I added 3 tsp 6% bleach to bring it to around 50FC. In an hour I tested it to be around 3 FC but when I left it sit a second it turned pink again. In fact if I let it sit for a few minutes it turns brilliant pink and tests another 3. Is this my high cya (just over 100) affecting test results? I'm a bit confused.
 
Turning pink after some time is usually a high Combined Chlorine (CC) level since it will eventually react with the dye (from some scientific papers I read that waterbear referred me to -- I think). So after it first turns clear, add the R-0003 reagent to test for Combined Chlorine (CC) and given your earlier results on your pool it should turn pink when you add that reagent. Then count the drops from that point to get a CC number.

It does seem like your water is full of either ammonia or monochloramine and that it's taking lots of chlorine to oxidize it. With your previous relatively low CC numbers, it's more likely to be ammonia. With high CYA it can take a minute or two for chlorine to combine with ammonia, but I'd then expect to see higher CC numbers which is why I'm asking you to test for CC after FC when you do your bucket test and would like you to test it after 5 minutes, not an hour.

I believe the ammonia tests used for aquariums are very inexpensive (< $10) so would be worth getting as well. If you've really got tons of ammonia in the water, then you'll need to decide which is less expensive or easier -- partial drain/refill or lots and lots of chlorine.

There is one other extremely unlikely possibility, but I thought I'd put this out there since there are a few people who swear that high phosphate levels consume chlorine directly. We know that high phosphates promote algae growth so that can consume chlorine in fighting algae, but just in case these people are right it would be interesting to get the water tested for phosphates (probably at a reputable pool store). Though there is no known chemical mechanism for chlorine reacting with phosphates directly, maybe there is some sort of test interference. My hunch is that phosphates are not the issue here, but I'd like to be thorough and eliminate possibilities even if unlikely.

Richard
 
chem geek said:
There is one other extremely unlikely possibility, but I thought I'd put this out there since there are a few people who swear that high phosphate levels consume chlorine directly. We know that high phosphates promote algae growth so that can consume chlorine in fighting algae, but just in case these people are right it would be interesting to get the water tested for phosphates (probably at a reputable pool store). Though there is no known chemical mechanism for chlorine reacting with phosphates directly, maybe there is some sort of test interference. My hunch is that phosphates are not the issue here, but I'd like to be thorough and eliminate possibilities even if unlikely.

Richard
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Richard, you know as well as I do that this particular 'theory' has basically been propagated by the President and owner of a product company whose MAIN product is a lanthanum based phospahte remover and every time either you or I have asked him to provide a chemical pathway for this process he has coveniently ignored us and has not answered (including ignoring the email I have sent him personally!) I say it's just marketing hype to promote his product since his previous product of sodium percarbonate non chlorine shock proved to be a bust in the way he marketed it!
 
My phosphates tested at 300 and I'd tend to think ammonia except that my test results were a little interesting. I've added chlorine to this 5 gal water several times today. I added 3tsp, tested 1 hour later and had very little left, maybe 1. I added 2 tsp, checked a couple hours later, nothing.

Then I took your approach. I added 3tsp 6% (for 45 or so FC). I stirred for 5 minutes and took a sample. I diluted the 10ml sample to 20ml then poured off 10ml so each drop was 1 ppm. I got 17 drops before clearing. This means that 30ish ppm got used. I thought "well if it's 17 after 5 minutes maybe the ammonia is gone". So I left it for an hour and just tested 7ppm. I added another 3 tsp and will check in 5 minutes and after another hour. So basically I'm not there yet with my current chlorine purchase and dare not dose the pool with anything more than "maintenance" levels. Looks like I'll be getting that ammonia test kit.
 
Pools with very high nitrogen ammonia levels can take a very high dose of chlorine to clear. Dilution is a viable option since it will reduce the nitrogen load so the chlorine can handle it more effectively but the bottom line is it's going to take a LOT of chlorine in a very high dose to get rid of it. Sometimes it's necessary to go as high as 100 ppm!
Also you need to remember that I am talking about a pool with NORMAL CYA levels, not the over 100 ppm level that you have!
At this point I think your best bet would be a drain and refill of at least half the water to get the CYA to a more manageable level and then shock to a very high FC level. What you have been doing has not been working.
 
If I were to chlorinate to 100ppm... what do I risk in terms of equipment damage? How long would it be necessary to hold it or would simply reaching this breakpoint take care of it? I'll grab another bucket of water and test to see.
 
I tested ammonia today and the pool tested 6ppm. I tested the bucket that I have been working on (added equiv of 45ppm fc, 25, then 45 again) and it was 0. The bucket is also holding around 4ppm FC though I didn't try to add again.

I've read that you need 10ppm FC to combat 1ppm ammonia (a high side estimate). I also have 1ppm CC in the pool which suggests I need 10ppm FC to combat that. This suggests that I need a total ppm FC of 70. I have 76 on hand which suggests to me it will be enough even if I am off slightly on my gallonage calculation. I'm also not afraid to buy another 50 ppm or anyting like that to finish the job - unless someone suggests that I should dose higher or attempt to maintain the high level...
 
You are right about the 10:1 rule for the amount of chlorine ppm (measured as ppm Cl2) to oxidize ammonia ppm (measured as ppm Nitrogen). It's technically a little less than 10:1 (7.6 theoretical), but 10:1 ensures a complete breakpoint. As for CC (which ia also measured as ppm Cl2), you only need the same amount of FC to break CC so 1:1 in that case (again, it's technically less, 0.5 theoretical, but 1:1, is fine).

Richard
 
Okay, well I just want to post my course of action to be sure nobody thinks it's insane. I am going to add 10 174oz ultra bottles and 6 3 qt ultra bottles which should raise my ppm to around 76 (but it will rapidly go down due to the ammonia). I'm going to do this at dusk and leave the pump and filter running all night (though there's nothing to filter - it's clear and holding without requiring backwash). This is high enough that it should destroy all of the ammonia, CC, and leave a nice 10-15ppm FC residual. IF I destroy all the baddies and my FC is 15 and my CYA is just over 100, what rate can I expect the FC to deplete? I've seen others have it go down maybe 1ppm per day. That's what I would consider acceptable rate but I suppose with the high CYA I may need to use more.
 

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Piku, you may have found the reason for the high CL consumption but have you found the source of the problem? You said your main drain may be leaking. Could that be your source of contamination? If yes, then you better drain, fix and refill.

My 2 C.
 
vincent said:
Piku, you may have found the reason for the high CL consumption but have you found the source of the problem? You said your main drain may be leaking. Could that be your source of contamination? If yes, then you better drain, fix and refill.

My 2 C.
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Based on what the previous owner left in the garage, I believe that the last time the pool was used the CYA was creeping to sky high levels. Eventually there was algae that was tough to fight so they just closed it. Then it sat covered for 2-3 years while bacteria went to work eating the CYA and pooping ammonia and urea. During the summer a couple of small holes probably allowed algae to grow, live and die constantly creating more and more ammonia and urea. Eventually I probably had 10+ppm ammonia. This takes 100+ PPM FC to consume. If you don't shock it properly it turns to combined chlorine, requiring even more chlorine to consume. I *firmly* believe the source of the problem is ignorance and neglect and I believe that as long as I get my pool to be devoid of life and keep it that way, I will not have an ammonia problem any longer.

I haven't tested my source water, but I fill my fish tank with it and if the ammonia was 6ppm as tested out of the pool, those fish would be done for.

This is only a theory and I'm still not 100% sure ammonia is my whole problem, but I know for sure that it's a huge huge part of it.

I do not believe that my main drain is leaking ground water into the pool because I think my filter would be clogging much faster. It's been over a week and it's resting comfortably at 9psi. Also my main drain is producing air which from what I read is not waht would be happening if it was leaking. If it's leaking, it's *really* slow because day after day of no rain, the level in the pool is just fine.
 
I applied 76 ppm FC (10 @ 174oz 6%), (6 @ 3qt 6%) and after 2 hours took some tests. FC is 1 (as usual), CC is 12. Ammonia is around 3ppm left so it looks like I conquered 50% of the problem. I'm going to wait a week or two for the CC to dissipate on it's own or perhaps use a non-chlorine shock on it. My next plan is to use 4 2.5 gal 12.5% (70ppm) from the pool store ($30) IF I get the CC to dissipate, otherwise a lot lot more.
 

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For those that are following the saga, the pool is clean as ever. Ammonia tests 3 still, FC 0 and CC is 6. Hopefully by this weekend the CC will have burned off and I will be able to shock it again. I do believe a shock equivalent to what I did will take care of it. Since the ammonia was at the top end of the scale, it must have been higher than the strips can test. Now it's definitely in range. I have to hurry with this unfortunately. Temp hit 55 in the pool today already and rising fast! Algae will be coming around in no time.
 
Hello all, Went to my new pool store (builder/store) (a small mom and pop shop, SUCH NICE PEOPLE with the BEST PRICES in my area), and purchased 5 2.5gal jugs of 12.5%. I poured it into the pool, ruined my shirt (that stuff is serious compared to regular bleach!) and raised the FC to 87 according to poolcalc. I added it this morning because my CYA is so high and I figured the sun would do a good job of helping to burn off CC. The ammonia measured 4ppm early this morning and the CC was around 4ppm, thus 86 ppm of FC *should* take care of it. We shall see! Ironically this much easier to bring home chlorine is cheaper than walmart.
 
So after today's treatment, FC 1, CC 4, ammonia is between .25 and .5 PPM. I'd say I've just about kicked this problem. Let the CC burn off a bit (say down to 2) and shock it at 30-40 and I should have it. It's nice to be able to measure a parameter and see it declining and knowing that soon the pool will hold FC :p If anyone else has an ammonia problem, I'd highly recommend buying the test kits so you can see yourself conquering it.
 
We had what looks to be about an 1.5" of rain tonight. The yard flooded and dumped mud into the pool. Hooray :( I guess this is how the pool got so nasty to begin with. I'm filtering and hopefully it doesn't clog up overnight.
 
piku said:
We had what looks to be about an 1.5" of rain tonight. The yard flooded and dumped mud into the pool. Hooray :( I guess this is how the pool got so nasty to begin with. I'm filtering and hopefully it doesn't clog up overnight.
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I guess the next project is to try and change the drainage inthe yard to help reduce this from happening again.
Any pitures?

Iggy
 

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