Trouble reducing CYA

[rangies3]

Day One Test results:

FC = 1
TC = 2
pH = 7.2
CH = 590 ppm
TA = 130 ppm
CYA = 100 ppm

The kit mentions using "unstabilized chlorine" for a time to reduce CYA. What is this? The other option listed was partially draining. I drained the pool to about an inch below the skimmer baskets. I added a gallon of unscented bleach, then refilled the pool.

Day Two Test Results:

CYA = 100 ppm
CH = 410 ppm
I can't remember the chlorine level. I drained the pool again, this time to three inches under the skimmer baskets (maybe four). At this point, I'm assuming I must have mis-read the CYA test the first day. I added a gallon and a half of unscented bleach, then refilled the pool and ran the pump all night.

Day Three Test Results:

CYA = 70 ppm
Chlorine = 0
pH = 7.2
At this point, I'm thinking I'm on the right track, but need to drain the same amount as the previous day to remove another 30 ppm. I did. I had NO bleach left, so I added a package of shock (active ingredients listed 99% chlorine, 1% "other"), then refilled the pool and ran the pump all night. The kids wanted to swim, and I had to sanitize.

Day Four Test Results:

CYA = 90 ppm
TC = 1.5
FC = 0
pH = 7.2
CH = 360 ppm

I'm surprised that one package of shock could actually increase the CYA by 20 ppm. Do I have a bad test kit? I bought it at Leslie's and it was a big one which he recommended (PS employee). I'm about out of CYA reagent already. Could our hose-water (fresh) have CYA in it? Why is the chlorine disappearing so quickly while I'm bringing down CYA? I don't have algae.

Thoughts? Thank you.

 

[Guest]

Sounds like you shocked with dichlor or possibly granular trichlor. I suspect the latter based on what it said on the label. What was the actual ingredient in the shock that you used. Both dichlor are stabilzed chloirne and will add CYA with use. the unstablized chlorines that won't add CYA are the hypchlorites--sodium hypochlortie (bleach and liquid chlorine), calcium hypochlorite (cal hypo shock--the most common 'shock') and lithium hypochlorite.

If your CYA tested at 100 ppm it could very well be much higher than that, btw. It takes time and patience to lower the CYA. You won't do it over night!

As to why there is no FC it's simple. Your FC is not anywhere near high enough for your CYA. You might want to review the FC/CYA chart in pool school
category/pool-school/chlorine_cya_chart_shock
and while you are at it you might want to take some time to got through the rest of pool school. It explains a lot of what you are seeing (and you would have known the difference between stabilized and unstabilized chlorine and also which test kit to get! I am going to make a bet that the test kit you got is a DPD test kit, chlorine test uses a comparator block with different shades of red and NOT an FAS-DPD test kit that counts drops until the sample changes from pink to clear. Am I right? The DPD test will not measure above 5 ppm without dilutiing and can bleach out at high chlorine levels,)
category/pool-school/

Are you still using trichlor pucks in your feeder and running it wide open like you posted in your other thread? If you are you need to stop right away.

 

[rangies3]

Hello, and thank you for the lighting-fast response. DPD test kit, Sodium dichlor shock, and no more pucks in the in-line feeder or floatie (for many days now). Is the granulated chlorine (my father-in-law mentioned that he used it when they had a pool) stabilized? Or does it vary by brand? I need to go to the PS for the bubble thing on my polaris (has water in it). I'll look at what they have in granulated form and compare the cost to liquid bleach (which is on sale somewhere this week, have to check my shopping list).

I looked at the CYA/chlorine chart, and wow, it will take a lot of bleach. I'm still not too sure why I'm not getting more results from these drainings, and it's "shocking" (bad pun) that one pound of shock could raise the CYA 30 ppm overnight! They really should list these chemicals in the ingredients on the package! Sounds as if I didn't kill any bacteria for that afternoon family swim, and just created another reason for having to drain the pool AGAIN. Wow, a water bill from Hades is on the way.

I actually paid for pool school (someone came out and gave me step by step instructions on how to use the equipment). I can't say it was a total waste of money, because I'd never looked at pool equipment before. He did not get this detailed in the chemistry, just told me to add a pound of shock once a week or after heavy use or rain, and to keep those chlorine pucks stacked in the in-line feeder. I also heard the line at several pool stores about CYA not being harmful in large quantities, and/or that mine was "fine". Those test strips are a far cry from accurate, and cost a small fortune.

 

[frustratedpoolmom]

I just want to concur with Waterbear, the CYA test that uses the black dot - the tube goes up to 100. But many times, when the CYA is actually higher, it can take several refills to lower it below 100. Your CYA could have been 150 or more, hard to say.

Stick with liquid bleach for shocking, no CYA in there. Leslie's might sell more CYA reagent? Otherwise you can order it online.

 

[frustratedpoolmom]

Yes, unfortunately you are learning the hard way that pool store employees and even "pool school" instructors (Not Pool School here at TFP) are not well versed in the realities of pool water chemistry...

Strips are very expensive and very inaccurate. One powdered shock that does not contain CYA is Cal-Hypo but that contains Calcium and eventually that can get too high too, that's why we recommend liquid chlorine in most instances. Liquid chlorine a.k.a. household bleach is also the most economical.

Check out this thread for a cost analysis of the various sanitizers....

 

[Guest]

Sodium dichlor shock, and no more pucks in the in-line feeder or floatie (for many days now). Is the granulated chlorine (my father-in-law mentioned that he used it when they had a pool) stabilized? Or does it vary by brand?

Dichlor is stabilized chlorine. It actually adds CYA FASTER then the trichlor tabs do! For every 10 ppm FC added by dichlor it adds 9 ppm CYA !!!!!!!!!! (Trichlor will add 6 ppm CYA for every 10 ppm FC added.)
Granualted chlorine might or might not be stabilized. It has nothing to do with the brand but instead what chemimcal form of granular chlorine it is. It could be granular trichlor or dichlor (both stabiilzied and will cause CYA to rise) or it could be cal hypo or lithium hypochlorite (both not stabilzed and will NOT cause CYA to rise.) Take some time and read and study the pool school section of the forum. I think you will find it very helpful. Start at the top and work your way down since it's arranged in order.

As far as the costs of various methods of chlorination, you have to look at the TOTAL chemical costs and not just the chlorinen itself. Liquid chlorine is the most economical.
Bleach IS liquid chlorine. Check prices, sometimes liquid chlorine from the poolstore is a better buy, sometimes laundry bleach is a better buy.

 

[rangies3]

This afternoon, I tested for CYA again, and had a reading of about 65. That's a lot better. I needed a part for my polaris, and I discussed my CYA problem with the employees. They told me that in this area, liquid chlorine (or any unstabilized chlorine) is not sold or approved for pool use because of our unusually high temperatures and sun. They said that unstabilized bleach could not and would not stay stable long enough to keep the pool sanitized. They said that if CYA is over 300, then yes, it would block chlorine stabilization, but at the levels I'm getting it shouldn't be a problem. They told me instead to look at phosphates, because we have trees overhanging our pool. They said phosphates will prevent chlorine stabilization, and promote algae growth. They had just sold their last bottle of CYA reagent, so I'll need to buy more. Meanwhile, my CYA levels are a little lower this afternoon than they were this morning. With the replacement part to my polaris, more of the organic matter which dumps phosphates into the pool will be eliminated. Another interesting thing they said is that CYA will bind with the plaster in the pool. When I drain and refill, CYA will leach from the plaster back into the fresh water, and go right back up. Over time, it will dissipate, but they said it could take more than a month of daily draining and refilling to get the absorbed CYA out of the plaster.

All of their information sounded a little conflicting: CYA under 300 shouldn't block chlorine, yet CYA at 100 could leach into the pool from its walls.... They want me to bring in a water sample to test for phosphates. I didn't have time today.

Any further input on this information?

Thank you so much!

 

[JasonLion]

Wow, there is so much misinformation there, it is difficult to know where to start.

Liquid chlorine does break down when it gets very hot for a long time, but that generally takes a while. If you use it within a reasonable time of purchase you should be fine. Once it is in the pool it is exactly the same as any other form of chlorine.

The higher the CYA level, the higher the FC level you need to maintain to keep the pool sanitary. That keeps on being true up to extremely high CYA levels. In practice, it is very difficult to get to the FC levels you need to have when CYA is above 90, but it can be done.

Phosphates are almost never a problem. The primary purpose of phosphate remover is to make the pool store more income. If you maintain the correct FC level for your CYA level you won't have algae problems, regardless of your phosphate level.

It is possible for CYA to go back up a little after you lower it. But this effect is minimal and is usually the result of testing error. Once you lower the CYA level it might go up just a little, maybe, probably not. If it does, one additional partial drain and refill will take care of it.

What is much more common is that CYA levels over 100 can test as if they were 100. Then when you lower the CYA level, it will still read as 100 because it is still above 100.

If your CYA level is actually 65, then you don't have a CYA problem and shouldn't be worrying about anything they said.

 

[Guest]

Where are you located? Here in FL liquid chlorine is sold at just about EVERY pool store in the state. One thing you might want to tell them if you go back there. If you have CYA in the water and add unstabilzied chlorine like liquid chlorine or bleach it becomes stabilized chlorine because it reacts with the stabilzier in the water. That is why stabilizer is added to pools! I hate to say it but they are trying to sell you a bill of goods to keep their profits up!!!!!! I know a bit about this. I work in the industry!

Phosphates have NOTHING to do with chlorine stabilzation and phosphate removers are one of the biggest scams that pool stores have inflicted on custmers since pool magnets that were sold to reduce scaling and kill algae! There ought to be a law! This is the kind of thing that makes me ashamed to work in this industry!


Next time you go to this store be sure an wear boots because the BS is really deep!

 

[Swimgirl]

Here in the Tucson area, where temperatures are often around 105, liquid chlorine is sold in pool stores, in the pool sections of Home Depot, Lowes, and even several grocery stores. Although I do remember that in the pool store where I bought my pool, they did recommend stabilized chlorine only. But, anyway, even if you do get a recommendation like that, just don't listen, and look in other places for your liquid chlorine.