Is there an ideal cyanuric acid level?

[peatree]

Looked through all six pages and could find no thread. I'm a newbie and would like to know if there is an optimum concentration for CYA. If a thread was missed massive apology for the redundancy. Thank you for providing such a valuable library of information.

[Watermom]

Hi and welcome to the Pool Forum! For most pools, CYA in the 40 to 50 range is what we suggest. Some folks in really hot areas, deliberately run theirs a little higher to help them keep chlorine in the pool. Hope this helps. Let us know if you have more questions.

[peatree]

Thank you, kindly.

[Watermom]

You are most welcome.

[bobcat]

So maybe 60-70 for Central Texas?

[aylad]

I would start at 50-ish, let it stay for a week or so, and see how much chlorine you lose in a given day. Then bump it up to 60-70, and see if your daily chlorine loss lowers. If so, then you can stay there or maybe bump it up just a little more. If not, then it's not hard to backwash out 10-20 ppm CYA to get it back down to the 50 range. ;)

I'm close to Shreveport LA, and I keep mine in the 80-90 ppm range, but my pool is in full sun all day. I find that with a CYA of 40-50, I lose approx. 4-5 ppm chlorine in a day. At 80-90, that daily loss drops to around 2 ppm.

Just remember that as you raise your CYA, you must also raise your minimum chlorine levels (see the link to the best guess chlorine chart in my sig). I know it seems like you're still using more chlorine, but once you get to your required baseline, it still uses less to replace 2 ppm daily than it does to replace 4 ppm.

[peatree]

Thank you again for your bountiful information. After reading several times, I finally "get" the necessity of keeping the pH so finely tuned. Thanks to:

http://richardfalk.home.comcast.net/~richardfalk/pool/OBrien.pdf

This was found reading your site. (It would be so satisfying to have found this on my own!)

The key features are
p 21. HOCl is 80 times more bactericical than Ocl(-)
p 23. The dotted lines for HOCl and Ocl shift with very slight pH shift, due to y-axis being logarithmic.
p 25. HOCl is more stable than OCl in sunlight.

Right now CYA is ~50 ppm and we'll see how it works out. As your site illustrates, it is easy to raise, but lowering is more difficult.

THANKS!

[PoolDoc]

If you read O'Brien, you should look for Richard (Chem_Geek) Falk's threads here in the China Shop, and at TroubleFreePool.com in the Deep End section, and get a copy of his spreadsheet.

I don't have time to get into it now, but there is not an "ideal CYA level". There are necessary levels of HOCl for effective algae and bacterial control. But those vary with CYA level, more strongly than with pH.

OBrien lays the ground work for that, but as far as I know, Richard is the only one who has covered it in detail. My own "Best Guess" chart was, and still is, the *practical* applications of those ideas, which I picked up from OBrien via John A. Wojtowicz, and combined with my own field experience. Richard picked the practical application here, about 10 years ago, and took off from there. He found OBrien, got a copy, and was able to get republication permission for a paper long out of print . . . which is why you were able to find it on his machine.

But, at least compared to the conventional pool industry, the BBB method taught here, DE-EMPHASIZES
the necessity of keeping the pH so finely tuned. because, as you can see in OBrien, the HOCl levels are not nearly so sensitive as they are in a stabilizer free pool.

[Airren]

I have a CYA at over 100 - yes I am in the deep south, but I think this is not really good. How can I lower it?

[PoolDoc]

The only practical way to lower it is to drain and replace water . . . which is pretty wasteful and expensive, and which can destroy vinyl pools if not done professionally.

There is a way to drain in place, using a tarp larger than your pool, if it comes to that.

BUT . . . there is another alternative:

1. Buy a K2006 and find out what your CYA level really is -- you'll have to do a 1:1 dilution with tap water, test, and then double the reading. (Test kit info page, here. (http://www.poolforum.com/pf2/showthread.php?14994) You'll also need the K2006 and CYA test in order to know how much to drain.)
2. Adjust your 'ideal' chlorine level according to the "Best Guess Chart" in my signature.
3. Chlorinate just one time per week with bleach or cal hypo (or get an SWCG)

Doing so is a lot less expensive than draining and refilling, and won't waste water. Your CYA will gradually go down over time, especially if you are backwashing a sand filter.

[JimK]

Hi and welcome to the Pool Forum! For most pools, CYA in the 40 to 50 range is what we suggest. Some folks in really hot areas, deliberately run theirs a little higher to help them keep chlorine in the pool. Hope this helps. Let us know if you have more questions.

The owners manual for my Aqua Rite salt water chlorine generator says to maintain CYA at 60-80 (80 being ideal). Is there a particular reason this higher level is required? Would maintaining the lower level you suggested (40-50) have any negative affect on my SWCG (shortened cell life, etc??)?

Thanks.

[BigDave]

CYA of 40-50 is the general recommendation for manually dosed pools. For SWCG pools, the recommendations you'll find here are to run CYA at the top of the SWCG manufacturer's suggested range to reduce the load on the cell and extend it's life. You do need to keep your FC at the appropriate level for the CYA level you have.

[PoolDoc]

Is there a particular reason this higher level is required?

Yes, it has to do with the chemistry at the electrodes, as well as the issue BigDave mentioned. I think it's been covered in the China Shop by Chem_Geek, but I don't have time to go poking around for it right now.

But, your cells will last longer that the higher level, since cell life is proportional to ON-time, and they'll be on less at the higher CYA, even with the higher required chlorine levels. Read through the Best Guess page, linked in my sig, for more info.

[JimK]

CYA of 40-50 is the general recommendation for manually dosed pools. For SWCG pools, the recommendations you'll find here are to run CYA at the top of the SWCG manufacturer's suggested range to reduce the load on the cell and extend it's life. You do need to keep your FC at the appropriate level for the CYA level you have.


Yes, it has to do with the chemistry at the electrodes, as well as the issue BigDave mentioned. I think it's been covered in the China Shop by Chem_Geek, but I don't have time to go poking around for it right now.

But, your cells will last longer that the higher level, since cell life is proportional to ON-time, and they'll be on less at the higher CYA, even with the higher required chlorine levels. Read through the Best Guess page, linked in my sig, for more info.

Thanks.

[robbym70]

This is CYA related but not sure if I should start a new thread??




1. Buy a K2006 and find out what your CYA level really is -- you'll have to do a 1:1 dilution with tap water, test, and then double the reading.

@ PoolDoc-What does you mean about the 1:1 dilution. I have a K2006 and I think my test method involves filling the sample tube to about half full then balancing it off with the regaent....then transferring to the comparator until the black dot disappears from above.

I don't understand your reference to the 1:1 dilution. Am I missing something?

My CYA has been consistently below 30 (black dot always visable) since I've been testing. This year I want to address this by adding stabilizer to bring it up to the recommended ~ 40-50 ppm.

Would it better to run with Trichlor pucks to bring up the CYA level or simply place stabilizer in the sock and place it in front of the return.

Since opening I've been using Robelle Shock Treat which is 12.5% Sodium Hypochlorite. I'm adding about 1/2 gallon every three days or so and this keeps me somewhere between 3-4 ppm for FC. When this runs out I was planning on switching back to 6 % bleach.

The water is sparkling clear at the moment. I've been following BBB since we bought the pool (uh, I mean the house) Last year (my first with the pool) I opened to a green mess but with the help and advice listed within this forum it cleared up in 2-3 weeks. Lots of bleach, a little polyquat and the much needed POP!

The former owner used and left behind a big tub of trichlor tabs. I used them up last year (about half the tub ) If the previous owner used these pucks regularly why is my CYA so low. Did the green mess last spring bring it down to zero somehow...and wouldn't the month and a half or so of using the triclhor pucks have brought up the CYA so it at least registers on the test?

No real urgency on this as I know you are busy with real pools in real life.

_______
23,000 Gallon AG - 30' round
Vinyl Liner
1 HP Hayward Power Flow LX
Sand Filter

This is CYA related but not sure if I should start a new thread??

[PoolDoc]

+ 1:1 dilution for CYA testing means, take your water sample and mix it 50:50 with tap water, and than test that mixture for CYA. (So, you end up with 1/4 pool water in your mix bottle.)
+ Trichlor tablets; dichlor is a fast dissolving granular material
+ Low on CYA? Use trichlor exclusively to chlorinate till they are used up. Only use bleach to boost chlorine levels if they get too low. (Do NOT pour bleach on top of tablets!!!)
+ Add borax as needed to maintain pH. (You can add borax on top of trichlor -- one of the very few chemicals you can do that with!)
+ A 30' round 48" pool holds about 18,500; a 52" holds about 21K. I put that in your signature.

[robbym70]

Thank you thank you...

Will pick some trichlor pucks up this week.

I understand WHAT it means to dilute I'm just confused as to WHY you suggest it. Your method with dilution doesn't match the method described in the test kit so I'm wondering what is the purpose for testing a diluted sample for CYA as opposed to a standard unaltered sample straight from the pool?

I got the 23,000 gallon number off the Robelle site. Either I miscalculated or they have it wrong. Thanks for fixing it.

I'll keep testing of course but how long will it take approximately to bring the CYA level up using Trichlor tabs......month, two months, whole season? I ask this because I used them for approximately a month or so last year and still had less than 30 CYA (black dot totally visable).

If the CYA doesn't come up ...oh forget that... we'll cross that bridge later if we have to.

Thanks again. I know how busy you all are and how much time answering these questions takes.

[aylad]

Pooldoc suggested the diluted sample for the CYA test to get a more accurate reading of what your CYA really is--if it's over 100, we don't really know HOW FAR over 100 it is, so if you dilute the sample, test, then multiply by 2, we get a better idea of what it really is.

If you're using trichlor tabs, it won't take long to get the CYA levels up, especially if they're in a feeder set at the highest setting. As a rule of thumb, for each 10 ppm of chlorine the trichlor provides, you're also raising your CYA by about 6 ppm. So...it won't take long at all to start seeing it come up.

Very often (and even more often last year!!) you'll see the CYA in a pool drop, sometimes to zero, over a winter if the pool is allowed to go green. There is bacteria related to the bloom that will "eat" CYA and then "poop" ammonia, which on opening takes a huge amount of chlorine to overcome. If you saw your CYA drop, that's likely what happened to it.

Don't hesitate to ask questions--we take the time to answer them because we enjoy being able to help others enjoy their pools--that's what we're here for! :)

[PoolDoc]

Will pick some trichlor pucks up this week.

Sorry, I misread -- I thought you said you still had 1/2 tub. Don't buy them for that purpose. Decide how you want to go first. If you DO get trichlor, or dichlor, get the from Sams Club in "PoolBrand". That product line is one of the very few that's unblended . . . and it's VERY cheap.


I understand WHAT it means to dilute I'm just confused as to WHY you suggest it. Your method with dilution doesn't match the method described in the test kit so I'm wondering what is the purpose for testing a diluted sample for CYA as opposed to a standard unaltered sample straight from the pool?

Allows test of levels over 100 ppm.




I got the 23,000 gallon number off the Robelle site. Either I miscalculated or they have it wrong. Thanks for fixing it.

Nah. They didn't "miscalculate": they know what they are doing. "Bigger" sells -- so they all calculate volume at the 'spilling over the edges' level.



I'll keep testing of course but how long will it take approximately to bring the CYA level up using Trichlor tabs......month, two months, whole season?

Since you don't have trichlor (my bad) if you have access to Sams, get either their PoolBrand shock bags OR their 50# bucket -- both are cheap; both are unblended.

[Watermom]

I think if it were my pool and I needed to add some CYA, I'd just add some straight CYA and be done with it. If you buy the big 50lb. bucket of tabs, you'll have many left over for another year, which is ok if you keep them dry. But, if you don't want to store that bucket, just buy some stabilizer. Or, as Ben also suggested, the bags of shock are dichlor which you could also use and wouldn't have to buy such a large quantity of it....... I don't think. (?)

[robbym70]

Thanks guys...Great help as usual.

By the way. I have a Wanda The Whale coming this week...largely in part to your recommendation W.M. I rather enjoyed doing the vacuum work by hand last summer when it was warm enough to be in the pool. It did take a lot of time though and I'm hoping Wanda works like a charm.

[Watermom]

I think you'll be pleased with Wanda. I actually have two different auto vacs. Wanda is good for walking around getting dirt and little stuff and my Polaris 65 is good at getting big stuff. I use the Polaris more in the spring when the trees are dropping lots of stuff into the pool and again in the fall when the leaves start dropping. The rest of the summer I use Wanda. Having said that, like you, I also enjoy vacuuming manually while in the pool. It does take awhile but in all reality, I can get the pool cleaner that way than using Wanda or Polaris. So, I still do it that way at times. But, Wanda is nice and I can be lazy and let her do the work! Let us know how you like it.

[robbym70]

Very pleased thus far with Wanda. As long as the pump doesn't lose prime she runs for hours unattended...

Back on the CYA issue...

I decided to buy a smaller bucket of trichlor pucks...but I did not have a chance to go to Sam's club. I bought a 15 pound bucket of Robelle Jumbo (Slow dissolving) tabs. Now I'm worried after reading Ben's posts about many manufacturers using fillers. I'd like to list the ingredients as listed and confirm this product is okay. If someone with the knowledge could chime in that would be very helpful.

Ingredients listed as

Trichloro-s-triazinetrione*.....99%
Other Ingredients .................1%
Available Chorine.................90%

*trichloroisocyanuric Acid Dry

Thanks in advance. I know how busy you are moderating. I appreciate your time and help.

[robbym70]

Okay...I think I answered my own question. I compared the Kem-Tek product to the Robelle product...same exact active ingredients so I think I'm okay with the Robelle product.

Bought it at Benny's (SE MASS) which is a smallish family owned department store...

No reply necessary unless I've missed something. Thanks in advance anyways cuz I know you probably took the time to read it.

[PoolDoc]

. what you got is fine. -ben