CYA Levels

[lilebelle]

First I have to say thanks to Ben and all of you for your years of experience & help that make it easy to have a pool. I have used the forum info for several years and it is a blessing indeed – even with a pool with an ionizer. We had nothing but success & easy water for several years with the ionizer & this forum (until the unit died) & the info in this forum mostly applied across the board to the basic daily care. My other half plans on restoring the ionizer, but time is not on my side for summer swimming. As for the forum – IT LIVES!!!...and eveyone is glad!!!! Hopefully with time most of the ’lost’ info will be restored.

Now to my question:

It may already be here, but I haven't found it, yet....

When adding CYA, how much will it raise the CYA in a pool?? The container says 3 pounds per 12,000 gallons if your CYA is less than 40, but does not indicate how much of an increase to expect. I will be adding through the skimmer and giving it 2-3 days to see where it will level off, but I'd like to avoid overshooting. Current level is less than 30, but not totally gone.

Pool is 33’ x 54”, ~34000 gallons, AG, sand filter, round with ~25’ diameter centered bowl, depth of 6 feet @ center of bowl, in South Carolina.

Results this evening were:

Water Temp = currently averaging about 50F, give or take 5 or so depending on ambient temps
pH = 7.2 - holding steady...
FC = 7.5 – will have added 3#’s of CalHypo by the time you have read this to inc FC by ~6/7ppm
CC = 0.5
(TC = 8.0)
TA = 130
CYA = Confirmed at <30>0
CH = 70* due only to using CalHypo recently

It appears that I am losing ~4ppm in FC out of ~5ppm added over a 12 hr period.

Have been using bleach, but it kept dropping pH below 7.2, even adding Borax, so I switched over to CalHypo using the better way to add CalHypo for awhile, hoping to help ‘stabilize’ the pH & TA, and it has worked for the pH. I will be adding more Borax to push the pH up after the CYA has been added, and also watching the TA to keep it from rising too much. Back to bleach after that.

Water is now clear, liner looks mostly blue, as it should, but I do have a little green algae on the liner that is proving stubborn in some spots, so I had made an effort to keep the FC between 10-15, which was working until the CYA levels dropped below 30 and I was out of town for a couple of days - I’m the designated ‘Pool Guy’. The CYA levels came from using TriChlor late last year for a while. With the ionizer, I never needed to worry about the CYA levels.

Also, when I add the CYA, how long is a safe waiting period before adding anything else through the skimmer? I can always add bleach directly to the pool to boost the FC & to avoid unexpected surprises in the filter.

Thanks.

[mwsmith2]

When adding CYA, how much will it raise the CYA in a pool??

You can use my bleachcalc for that, look under "other calcs". Generally all CYA is of the same strength (darn near close to 100%, if it's not at 100%) so it should work for you.

It appears that I am losing ~4ppm in FC out of ~5ppm added over a 12 hr period.

Yeah, you may have some nasties in there that need cleaning up. Could be from CYA degradtion.

Have been using bleach, but it kept dropping pH below 7.2

Woah woah woah, hold the phone. Bleach does not drop your pH. If anything, it will make it rise. Bleach has a pH of 13. If your pH keeps going low, something else is at work here. You wouldn't happen to be using Cl pucks would you?

Michael

[duraleigh]

Good morning,

Search for a post from Michael Smith and download the calculator he has available in his signature. It has several very helpful calcs, including CYA, if you click on "more calcs" in the upper left hand corner.

Your losing a lot of FC so I'd think you are noticeably lower than 30ppm in CYA. To my knowledge, there is no harm in adding other items immediately after adding CYA. Others take a more conservative approach.

As you are probably aware, after you add the CYA, it will not show up in the test for a few days....mine took about 4-5 days if I remember. My assumption is that it takes that long to become completely effective as well so I'd go ahead and get it in there.

If my memory serves me correct, bleach has a pH higher than pool water....not lower. You've got a good handle on your numbers so I wouldn't change any of what you're doing but I don't think bleach was the culprit in lowering your pH.

If you've still got that little bit of algae and your CC tests a true .5 or more, I'd bring my FC up to about 12-15 and "shock" the pool. That'll get the CC to less than .5 and get the algae out of there, too.

Dave S.

[duraleigh]

Michael,

"great minds think alike"!!!!!

Dave S.

[leejp]

According to Ben...

_Stabilizer_____Min FC____Max FC___Shock FC
_______ 0________1________3__________10
_10 -__20________2________5__________12
_30 -__50________3________6__________15
_60 -__90________5_______10_________ 20
100 - 200________8_______15__________ 25

All Units in PPM

I plan to switch to the 3B regimen. Question is what CYA level? Pool is in full sun 8~10Hrs/day in upstate, NY (temps range from high 60s to mid 80s in season). What are the pros/cons of low/high CYA?

[duraleigh]

Hi, Lee,

Without a SWG, 30-50 CYA seems most popular. I'd start low at 30 and then move up a little if you don't think your CL is holding like it should.

If you get a SWG, I would follow Manufacturer's recommendation...usually 60-80ppm.

Dave S.

[leejp]

Hi, Lee,

Without a SWG, 30-50 CYA seems most popular. I'd start low at 30 and then move up a little if you don't think your CL is holding like it should.

If you get a SWG, I would follow Manufacturer's recommendation...usually 60-80ppm.

Dave S.

At 30-50 CYA the min recommended FC is 3 PPM. I don't have Ben's test kit (yet). I'm lookinfg through the test kits I have (OTO... is this a FC or TC measurement?) and 3 PPM is the max the kit'll measure (recommended is 1.0~1.5) Does Ben's kit measure beyond 3 PPMs?

I do have to say I'm a bit nervous... I've had iron staining problems and with high FC, I'm afraid that the iron will be forced out of the water onto the liner. Man I have to get that iron out of the pool!

I guess the danger in running lower stabilizer levels is that the FC will "burn off" quicker on hotter days.

[duraleigh]

Hi, Lee,

Ben's kit has two tests for Cl. A daily, easy one that goes to 5ppm and a drop based slightly more time consuming one that lets you test to shock value (up to 50ppm or so, I think)

I'm beginning to think metal in the water is the new "global warming" issue. I can not remember so many folks having metal problems. Yes, you need to get that resolved....your life will improve.

I guess the danger in running lower stabilizer levels is that the FC will "burn off" quicker on hotter days.

Bingo!! Get the kit (or one that measures FC, TC, CYA, CH, pH, and Alk.) It's the best money you'll spend

[SJohnson]

Everyone should read "WATER CHEMISTRY FOR SWIMMING POOLS"

Here's a link:
http://www.deh.enr.state.nc.us/ehs/chem.htm#ta
There's also a chart on that page that will show you how much certain amounts of cyanuric acid will raise your CYA levels. I've found it handy to keep a printed copy of this information lying around . . . Many people advise dissolving CYA in a sock(pantyhose) placed in skimmer . . .

Also, there was an article by PoolDoc(Ben) on the advantages of high CYA levels, which was interesting but I can't remember if that was on the forum or in poolsolutions . . . anyone remember where that was?

CYA exerpt from "WATER CHEMISTRY FOR SWIMMING POOLS":

"Stabilizer - Cyanuric Acid
Hypochlorous acid is a highly unstable molecule which dissipates rapidly in the presence of sunlight. This results in considerable loss of free chlorine from pools exposed to sunlight. Proper stabilization of chlorine with cyanuric acid slows the rate of chlorine dissipation without appreciably sacrificing oxidation and disinfection activity. Reaction of free chlorine with cyanuric acid produces a form of combined chlorine (chlorimide) which is active enough to aid disinfection and show up as free chlorine residual on your test kit. Proper stabilization requires 30 to 50 ppm cyanuric acid. Outdoor pools should be initially treated with 40 ppm cyanuric acid.

Cyanuric acid dissolves very slowly and is best predissolved in warm water before introducing into the pool. If it is not predissolved it may take several days to dissolve completely. Once added to the pool, cyanuric acid does not dissipate. It is removed from the pool only by splash out and backwash waste. Stabilized chlorine products such as trichloroisocyanuric acid will add stabilizer to the pool and may cause a gradual rise in cyanuric acid concentration. Excessive amounts of cyanuric acid can interfere with the disinfection process and at concentrations above 100 ppm may cause "chlorine lock" and clouding of the pool. Cyanuric acid level is lowered by draining part of the water out of the pool and diluting the remaining water with fresh water. Generally cyanuric acid level should be kept below 60 ppm. Stabilized forms of chlorine should not be used for superchlorination because cyanuric acid level may be increased. "

[waterbear]

(OTO... is this a FC or TC measurement?) and 3 PPM is the max the kit'll measure (recommended is 1.0~1.5) Does Ben's kit measure beyond 3 PPMs?

I do have to say I'm a bit nervous... I've had iron staining problems and with high FC, I'm afraid that the iron will be forced out of the water onto the liner. Man I have to get that iron out of the pool!

OTO measues total chlorine. Some people say that if you read the test withing 15 seconds you can get a free chlorine reading and then let it sit for about 2 minutes to get your total chlorine reading but it is a rough guide at best. If the color gets darker upon standing you most likely have combined chlorine but I would not trust it to tell you the amount.
Ben's kit has both OTO and FAS-DPD titration tests. The OTO test is good for a quick check on your levels(and Ben's wil measure to 5 ppm I believe) which in theory should be done daily and the FAS-DPD test will be able to test levels up to, I believe 50 ppm free and combined chlorine with an accuracy of either .2 or .5 ppm and would be your weekly test or your test when there are problems.
Bad news about the iron, unless your pool water is replaced or you filter all the pool water with an iron removing resin it will stay in your pool. When conditions are right(wrong?) it will deposit in your pool as a stain. When you put in a metal treatment it will dissolve back into the water. Nothing wrong with adding metal treatment when needed. If you are very lucky , when it deposits out of the water it will do it in your filter medium and not in the pool and it can then be removed by changing the filter medium. Works out well if you use DE, pretty costly if you use a cartridge.