Is there an ideal cyanuric acid level?

[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. (?)