From Blue to Green in 2 days

[therolf]

To say "confused" is an understatement. Reading a ton of messages pertaining to this subject, as well as trying to correlate the answers with my own experiences over the past 20 years, I arrived at an impasse.

The information at the Chemical forum seem to augment my suspicion, that the high CYA reading is the cause of my current dilemma, which is further corroborated by the opinion of my pool supply company.

The current problem, manifested itself within one week, even though I believe the cause dates back to last season, when I was unable to maintain a chlorine level above 2 to 4 ppm, running the chlorinator fully open at 8, when previously a setting of 3 sufficed.

Starting out I had a free chlorine reading of 2, PH of 7.0, Alkalinity of 80.
Added ca. 2k gallons of water, and shocked the pool with 3 bags of Leslie's Power Powder Plus.
Took another reading a couple of days later, since normally it takes about that long for the excess chlorine to dissipate. (FC 1, PH 7.2, Alkalinity 90)

Three days later it rained (6 to 8 inches) rain and the water got a tad cloudy.
Shocked again with 4 bags of Power Powder Plus. (Recommended shock treatment is 1 bag per 16,000 gallons).
Within 3 days, the water turned green and today it could be mistaken for a Louisiana swamp.

Took a water sample to my Pool Company and had them test for cyanuric acid. Their test showed about 150 ppm, and your chart indicates that the free chlorine has to exceed 39 ppm at 100 ppm stabilizer.

Here lies my confusion. One post on your site claims that the cyanuric acid diminished over the winter months, which mine obviously did not do, other information found indicates that CYA accumulates and the only way to reduce it is by draining some of the water.

I think, by writing this post I may have answered my own question, but would appreciate a little clarification.

Super chlorination (>10ppm free chlorine) will kill algae?
Why then does high CYA require 39 ppm chlorine for shock treatment

Please pardon this lengthy post. I hope that someone has the patience to read through it and help me with this quandary.

Rolf W.

 

[JasonLion]

You should do some reading at Pool School, several of your questions are answered there. I'll try to do a summary of some of the high points.

Shocking the pool is a process, not something you do and then you are done. If you don't monitor and maintain the FC level at the correct level the algae might not all be killed and can bounce right back worse than it was before.

CYA reduces the effectiveness of chlorine, so your need higher FC levels to be effective. The trichlor tablets that you are probably using in your chlorinator contain CYA, so the higher you turn up the chlorinator, the more CYA there is in the pool, the more chlorine you need. I think you can see where this is going, because once your CYA level gets up there there is no catching up.

One thing that helps a great deal is to get a test kit with a FAS-DPD chlorine test, which can reliably and precisely measure FC levels above 10.

Another thing to watch out for is that a CYA level of 100 might actually be much higher. The most common CYA test reports levels over 100 as if they were 100.

 

[jcourt]

Welcome therolf!

The first item I would attack is the high CYA level. CYA accumulates, and the only way to get rid of it is to replace water. According to the pool calculator, you'll need to replace 67% of your water to get the CYA from 150ppm to 50ppm. Might want to consider a complete drain and refill and bring up to shock levels to deal with the residual algae and then balance the water according to the pool school section of this site.

Jim

 

[Butterfly]

Hi rolf......another Texas pool owner :lol:

Yes, you did answer your own question. You do need to do a series of drains/refills to lower your CYA level.
Your pool is overstabilized. An ideal level for CYA would be about 50.

CYA tests don't accurately test over 100, so your CYA level could actually be even higher than the 150 the pool store mentioned.

The BEST investment we made in our pool is a good test kit. Do yourself and your pool a favor and order one.
Test kits compared here pool-school/pool_test_kit_comparison

Looks like a Louisiana swamp? We gotta' change that! :-D Welcome to the forum

 

[loughps]

therolf,

One thing I wanted to point out in your post:

Here lies my confusion. One post on your site claims that the cyanuric acid diminished over the winter months, which mine obviously did not do, other information found indicates that CYA accumulates and the only way to reduce it is by draining some of the water.

It can be confusing when you first come across posts about CYA, whether it sticks around or diminishes over the winter. What I think you'll find though is that in *almost* every case, the CYA you add is there until you drain and refill your pool. There are specific cases where folks have the CYA go away over the winter, possibly due to bacteria converting it to ammonia, but these are the exceptions (and just another problem you don't really want). Your experience with the CYA getting higher and higher is definitely the norm.

Read up at pool school and ask questions where you don't understand and follow the advice from the experts on here. You'll get it blue and maybe clearer than you ever thought it could be and the knowledge you'll gain will be invaluable.

Good luck.

 

[JasonLion]

CYA disappears over the winter for a fair number of people, especially if your FC level goes to zero over the winter and you get algae.

 

[therolf]

Hi JasonLion, jcourt, Butterfly, loughps

Thanks to all of you
I sure appreciate all the helpful info, and you managed to minimize or eliminate my confusion. From what I gather, it is CYA is the culprit for my debacle. It is just hard to use so called expert opinions, may they be from my pool store personnel or from the pool service company that cleans my neighbors pool. Many times, the information is correct, but incomplete or slanted to sell more product. My own experience over the past 20 years has served me well, until I ran into the CYA problem. It just didn't seem logical that higher FC levels are needed to kill the algae, just because some of it is attached to the CYA. When my neighbors pool guy told me that algae becomes immune to chlorine and that sometimes it requires three times the recommended dosage, I took it with a grain of salt, but when it worked I thought there was something to it. Sort of like the Chicago rats growing fat on Warfarin.
Well, I took your suggestions to heart and dumped about half the pool water this morning. Will wait for some more rain (San Antonio Code compliance issue) to vacuum and drain the rest. With all the information from your posts and the site it becomes apparent, that I may have to make an adjustment to my modus operandi. Namely monitoring the water chemistry even during the winter. For the past 20 years my pump was running 24/7 and the only adjustment was to the chlorinator flow reduction from three to one. It worked well so far, I always had a clean, clear, sparkling pool without ever hearing about the CYA issue. As they say, ignorance is bliss, but now the CYA caught up with me.

Thanks again, for the help. I'll let you know how it turns out.
Rolf W

 

[anonapersona]

Rolf,

Some of us have CYA levels that change in the winter due to wet winters. My pool overflow is situated such that the difference between needing to add water because the skimmers are sucking air and having the pool excess flow out the overflow grate is only about 2 or 3 inches. In the winter and spring we can easily get that sort of rain in a day. So in a wet (normal) winter my pool gets diluted by a lot of rain water. So I may see my CYA drop by some amount. Other people get that same effect from snow that melts on top of their pool.

OTOH, if you do not get enough rain or snow, the pool will have the same CYA as before. CYA does not evaporate when pool water evaporates, it is left behind so if you have dry winters and add water occasionally, you have not changed the CYA level.

It can be lost to splash out, if you have a lot of active kids in the pool, or draining, either by intent or by overflowing with rain or snow. And then there is also the total loss of CYA that some see over winter -- I don't totally understand that one but it seems to be related to 0 FC and possible ammonia problems. Not typical but we do read about it here.

 

[loughps]

therolf,

I understand how you feel. I loved the "experts" at my pool store until it got cloudy using their method and trips to the pool store started being $300 a month to add this and add that. Then it was do a partial drain and add this and add that, so I had the cost of chemicals AND water together. My frustration led me here. I read a lot over the winter two years ago and couldn't wait to order my test kit in the spring. Last year was my first year doing BBB all the time and my water was never more clear and I was shocked at how little I spent on chemicals (enough that I could actually deal with all my equipment issues last year!)

I'm still learning. I have a mesh safety cover and probably didn't let the water get cold enough before I closed this year (in northern Ohio, so we HAVE to close!) So, I had algae again when I opened up, but I was not afraid of it. I knew what to do and quickly got it under control. This year, I hope to use what I'm still learning and my goal is to open to a clear pool next year. But if not, I still know I have a better understanding of what's going on with my water than my pool store "experts" ever did!

Get a test kit, read, read, read and ask as many questions as you need to. At some point you'll get frustrated you didn't do this sooner.

 

[therolf]

anonapersona, loughps

Isn't it amazing, what you can learn from other pool owners, who are not out to sell expensive product? Yes, at one time, long ago, I thought I knew it all. But with age comes wisdom, and nothing is a better teacher than experience, which is freely shared by members of this site. Up until a few days ago I knew nothing of CYA, and the pool store sales people could only tell me that it was supposed to be within a certain range, but were unable to tell me why.
I don't winterize my pool, except for reducing the chlorine. Water loss due to overflow or splash out is minimal. Closed the overflow 20 years ago. So the only loss is due to evaporation, which naturally does not dilute the CYA.
Well, I'm on my way to turn the swamp back to a blue lagoon. Drained about 3.5 feet and vacuumed the the shallow side to waste. This lightened the dark green to a light turquoise. Tomorrow, I'll tackle the deep end. Prognosis: The war is won.

Rolf
Endeavor to persevere (The Outlaw Josey Wales)