Just when I thought I had everything under control...

[Yoav]

Hello,

I was not sure which forum I should use. Since this is my first post on TFP I decided this would be most appropriate.
Before I attempt to go into details, I figured I should open with the bottom line - my main questions.

1. Can CYA levels increase without using stabilized chlorine products?
2. Besides algae, what other possible causes of green tinted water are there?

I have read most of the Pool School entries, and gone over quite a few posts to try and figure things out myself, but eventually decided to post.
I will try to go over my history with the pool in hopes that some of the details will be helpful in finding out what's going on with my water.

I've become a pool owner almost year ago, and literally got thrown into the water. I got a pool with untreated water which turned out to have well over 100 ppm CYA, a pump at the end of its life, and an old and ineffective filter. So I read a lot, replaced the filter's sand, bought a new pump, and learned to do some PVC piping.

About 3 months ago I realized I had to replace the old water and start afresh [water is not something to be taken lightly here in Israel].
Having dealt with water full of CYA, I decided to go with liquid chlorine. My pool's coating is cracked and is undeniably a safe harbor for algae, but aside from a single bloom that happened when I was away, everything was mostly OK. I used a few pucks of Trichlor to get some CYA in the pool in the beginning and switched to Liquid.

Let me just point out that pool professionalism is not very common where I live. Almost everything I have learned I learned from the net. I have to bend over backwards to try to get anything resembling accurate water testing. I got so fed up with strips and tablets that I went out and bought an Extech electronic pH and ORP tester (it broke down about a month ago. Waiting for a placement unit to arrive)

Anyhow, not having the wonderful FC/CYA chart I found on your site, my aim was for 2-3 FC, which seemed to keep the pool clean.

Events that may be relevant:

1. Algae bloom two months ago while I was away - I superchlorinated to ~12 ppm, which turned my water to milk. The filter seemed to have a hard time removing it, so I went to my pool store and got a blue gel flocculant, placed it in the skimmer as directed and in one day the pool was clear again. I've been using it since in small amounts even though the pool store salesman said I should keep one in my skimmer at all times.

2. I started using our bubble-wrap-like solar pool cover about 2 weeks ago. Trying to save water and chlorine, but the temperature of the water was possibly reducing chlorine effectiveness.

3. Installed a 90% shading net over the pool mostly to avoid sunburn. I don't know what that has to do with water chemistry, but the trouble started somewhere near that time so I'm mentioning it too.

4. Had our garden redone in the past month. Could have had an effect if sand, dust, grass and fertilizer somehow got into the water in large enough amounts.

So, my problem started a week ago, when I removed the pool cover and the water seemed greenish. I could see the bottom, but the water wasn't clear. There was a bit of algae in some cracks, but overall, no slippery surfaces or anything.
I hit it with ~10 ppm of chlorine, but unlike previous instances of raising FC, it seemed to have had little or no effect at all. The green tint did not turn to white.
I then tried another 10 ppm, which seemed to be working in the right direction as the color was moving slightly to white but the water was not getting any clearer.
The thing that got me really confused is that it did not feel like algae - the color of the water, the feel, the surfaces - something seemed different.

What's more, the FC levels did not seem to drop. I would expect the algae to consume FC real fast as it has happened previously, but the chlorine seemed sluggishly content as if there was nothing in the water to oxidize (I am reserved about the accuracy of this account since as I've said before, my strips are not that accurate and the tablets' scale only goes as high as 3 ppm FC)

I eventually took a sample to the pool store where I got the following results:

pH - 7.1
FC - 5
TC - 6
CC - 1
CYA - 47

They don't have TA nor CH in their test. Go figure.
According to my test strips my TA is around 80 ppm (again, horribly inaccurate).

The thing about this level of CYA, is that it is considered normal, yet the amounts of FC required to keep a pool sanitized are 3 times as much as is technically allowed here (2 ppm max).
When I mentioned that I had not used Trichlor for a long time and couldn't figure out how CYA suddenly got so high (did it?) they said, it can slowly get back into a refilled pool from the walls, piping and filter... Is that correct?


I am really baffled by this turn of events. The possibilities I could think of are:

1. The gel flocculant introduced an unknown variable. perhaps Copper? could it make water greenish?

2. The gardening somehow raised phosphates in the water and aided the borderline algae to successfully outgrow the 2 ppm FC in the water.

3. CYA somehow spiked or has reached a critical point after magically increasing slowly and caused my FC levels to be inadequate. Obviously my 10 ppm shocks were totally inadequate but that does not explain why my FC kept being high. It should have been slammed down.

4. My liquid chlorine jug is in my shed which can get very hot during the day. The heat could have reduced its effectiveness to the point where I didn't really use correct doses. (if that were the case, wouldn't I have seen a reduction in the amount of FC levels being added since I use a specific cup for adding 1 ppm?)

5. The worst scenario - 2 different unrelated symptoms the same time. One unknown variable is coloring the water green but not effecting clarity, while the inadequate FC levels are introducing algae and hazy water into the mix.

What am I missing?

A final question:
Since 50 ppm CYA is way too much to my liking [ little kids ingesting too much 6 ppm FC water... ], I drained half the pool last night. Even though there is no circulation when its half drained, I put in 1.5 Liters of 12.5% liquid chlorine which should amount to ~20 ppm FC. I thought that despite not having circulation, I should see a change in the water which might confirm this was all simply a matter of an FC dosing error.
This morning though, the color of the water was unchanged, and still had clearly visible algae.
Could this amount of chlorine be ineffective as a result of no circulation?


I know I must have broken the longest-post-ever record. But this has really got me upset.
Thank you for your help.

 

[zea3]

Shocking is a process, not a 1 dose event. In order to shock your pool you need to bring the FC to shock level and keep it there until the process is completed. You are finished shocking when you pass the overnight test (lose 1ppm or less from dusk to dawn and you have .5ppm or less CC).

How often do you backwash the filter?

As far as the color of the water goes, if the pool surface is blue and you have iron in your water (yellowish) the combined color will appear clear green. You will need to test to see if there is iron in your water if this is the case.

You have mentioned several different CYA levels in your post. How is the CYA being tested? It will not rise on its own and does not accumulate in the plumbing unless you have the biggest pipes in the world! It is only removed by draining or reverse osmosis filtering. It does not evaporate out with the water. It can be destroyed by bacteria in the water but that is very rare. The test for CYA is subjective and based on when a black dot is no longer visible. It is difficult for computers or test strips to read it accurately.

You should order a FAS-DPD testing kit if possible. This will allow you to perform more accurate tests to take control of your pool.

 

[Yoav]

Thanks zea3.
After reading TFP I realized that shocking is a process, as well as the fact that I do not have the testing capabilities required to carry out proper shocking.
I'm also coming to terms with the fact that I must order kits from abroad if I am to have any accuracy or proper test coverage.

Even though "1-dose shocking" _seems_ to work for people around me (and for myself until last week), I still don't know why my water stopped responding altogether.
Thanks for the Iron tip. I will look up ways of testing for Iron in my water.

I almost forgot, now that my water's level is down - There is a white Silicon sealant between my skimmer and the pool wall thats quite torn and coming apart. Is there a special or specific kind of Silicone that should be used in fiberglass pools or is it a regular tube I can buy in any hardware store?

 

[piggyfarmers]

For us, there was no such thing as brushing too much the sides and bottom to filter dead algae, plus running the pump as much as possible. It took almost a week for us for the algae to clear up, and there were days I wasn't sure it was working and it tested my patience.

Is the 2ppm a legality involving private pools? You seem to be a perfect candidate for an FAS-DPD kit. You mention many factors but in the end what counts is getting the water levels balanced first.

 

[Yoav]

AFAIK, there is no official supervision over private pools, but the data distributed by pool stores and knowledgeable people is that FC max is 2 ppm and and TC max is around 3 ppm. Considering the recommendation that CYA should be around 50 ppm, it seems impossible to keep a pool sanitized with these numbers. Then again, everyone I know around me uses chlorine pucks and seem to be having no problems... I don't get it.

And I think thats what gets me. I had the TA where I wanted it (at around 120 ppm), I held the pH between 7.2 to 7.5 (that is the recommended range here), and I also managed to keep FC most of the time between 1 to 3 ppm using liquid chlorine. The only unknown variables were CYA which appears to have been at ~50 for quite a while and CH. Suddenly the pool stops responding to chlorine. Imagine my surprise. According to the FC/CYA chart I was simply plain lucky and it was just a matter of time before I got a nice algae bloom - which is what I am hoping has happened.

 

[piggyfarmers]

I've run across threads on this site that discuss the CYA/FC legality. Here's the first one I could find.
http://www.troublefreepool.com/basi...product-labels-t24424.html?hilit=FC legal CYA

 

[Yoav]

Shocking is a process, not a 1 dose event. In order to shock your pool you need to bring the FC to shock level and keep it there until the process is completed. You are finished shocking when you pass the overnight test (lose 1ppm or less from dusk to dawn and you have .5ppm or less CC).

How often do you backwash the filter?

As far as the color of the water goes, if the pool surface is blue and you have iron in your water (yellowish) the combined color will appear clear green. You will need to test to see if there is iron in your water if this is the case.

You have mentioned several different CYA levels in your post. How is the CYA being tested? It will not rise on its own and does not accumulate in the plumbing unless you have the biggest pipes in the world! It is only removed by draining or reverse osmosis filtering. It does not evaporate out with the water. It can be destroyed by bacteria in the water but that is very rare. The test for CYA is subjective and based on when a black dot is no longer visible. It is difficult for computers or test strips to read it accurately.

You should order a FAS-DPD testing kit if possible. This will allow you to perform more accurate tests to take control of your pool.

I just reread your statement about CYA tests - If I understand you correctly, you are suggesting that the pool store test results of CYA may have been inaccurate?
If that is the case then I am back to square one - No idea why my water went green and stopped responding to FC. (assuming of course that the CYA results were skewed upwards...)

As for backwashing, at first I got the impression that it should be done regularly, e.g once a week or once in two weeks. I did not like the idea since in our parts water is a scarce resource.
The more I read though, the more I realized that backwashing should be done when the pressure rises 8-10 psi above base pressure (which is around 4 psi in my case). I read that frequent backwashing is actually counter productive and that it may even cause media channeling.
I installed a pressure gauge on the top of my filter, and only had to backwash once since I've refilled the pool (~3 months) [bather load is very low in my case].

BTW, though I have no measurable way of verifying it, I feel that using the gel flocculant has indeed increased my filter's efficiency.

 

[Yoav]

I've run across threads on this site that discuss the CYA/FC legality. Here's the first one I could find.
http://www.troublefreepool.com/basi...product-labels-t24424.html?hilit=FC legal CYA

Thanks. I've read this post earlier today (while I was supposed to be working... )
I've also read another by Richard [chem geek] that confirmed my reasoning that regardless of CYA levels, when swallowing water, exposure to chlorine is proportional to TC (... mmm or FC... ), so that the higher the CYA, the higher the exposure to chlorine.

I've got two young boys who are just realizing they have a backyard pool and no matter how hard I try to keep it to a minimum - they take in quite a bit of pool water when they swim.
As an added bonus of keeping CYA low, is the fact that I want to water my trees when I backwash which means letting FC get as low as it can as fast as it can, backwash, and bring it back up; that is somewhat impractical with CYA levels of 50 ppm (at least from my experience with my pool)

 

[Yoav]

UPDATE: Since I've already drained half the water, I decided to get the paint redone.

I believe all the cracks and peeled-off paint, and possibly the white/blue discoloration, is probably just making the algae and sanitation problems worse.

I'll have to wait another week until a professional can come and get it done, but at least I'll get a clean start, and hopefully a less algae prone surface.

p.s does pool water pose a risk to a fiberglass body where the paint coat has cracked or has chipped off?

p.p.s That same professional claims a new coat of paint is good for about three years. Does that make sense? I see US products boasting a life span of 15-20 years :?

 

[chem geek]

I've also read another by Richard [chem geek] that confirmed my reasoning that regardless of CYA levels, when swallowing water, exposure to chlorine is proportional to TC (... mmm or FC... ), so that the higher the CYA, the higher the exposure to chlorine.

I believe you are referring to this post where I noted that the FC independent of CYA level is what matters in terms of total exposure from ingestion such as from swallowing the water, though I also noted that you'd have to drink an awful lot on a regular basis to get close to the EPA limits for drinking water. I also recently wrote this post where you can see that state and local regulations often ignore the EPA limit and set higher limits in commercial/public pools most especially when CYA is used. They almost, but not quite, have an understanding of the chlorine/CYA relationship. In practical terms, unless your children are drinking many cups of pool water every day or unless they are gulping it into their lungs regularly (they would be coughing as a result), then the risk is very low.

 

[Yoav]

Hi Richard,

I did read your post in its entirety. My intent of course was not to misrepresent your position on the matter.

There are two distinct facts that I learned from your post, one being a direct relationship between the level of exposure and FC, the other being the EPA limits set for that exposure.

When it comes to our individual health and that of our kids, my wife and I simply try to be on the strict side of things. I accept the relationship of exposure to FC as current scientific fact, whereas any limits set for that exposure are a matter of "more" than just science.

The science of determining what is healthy and what is dangerous for us humans is very complex and ever-changing.
When one considers safety limits and recommended allowances, how every society sets its own, it becomes more an art than a science (not to mention the cases where it becomes politics, business, etc...)

Where possible, we like to keep it simple and minimize risks as much as we can.

On a different note - I like experimenting. As I will slowly learn how to maintain a pool properly, my natural instinct for trying new things will probably make me make some errors here and there

 

[Thom53us]

Your Combined Chlorine was 1 ppm where .2 is the limit you are locked in combines and shocking should have cleared the pool. If you leave the solar cover on the chloramines can't gas off and remains in the water. Now it seems you can't filter the water because you lowered it to paint. When you do fill you should see test again and shock if your CC is over .2 ppm go 1ppm per combines if it's .5 go at least 5ppm in chlorine. I agree CYA is hard to test for so you should invest in a good test kit.


25000 gal. vinyl in-ground sand 1.5 hp hayward pump

 

[frustratedpoolmom]

Your Combined Chlorine was 1 ppm where .2 is the limit

a CC of .2 is not a problem at all; and one doesn't need to shock unless the CC climbs higher than .5. Even then sometimes just leaving the pool uncovered and slightly raising the FC level a few points higher than normal can help lower CCs without shocking.

and shock if your CC is over .2 ppm go 1ppm per combines if it's .5 go at least 5ppm in chlorine.

Ones shock level is ENTIRELY dependent on their CYA level. Refer to the CYA chlorine chart to see the recommended shock levels.

 

[Yoav]

Thanks Thom53us and frustratedpoolmom. You just gave me an idea.

If I take your statement "you are locked in combines" and assume that CC levels have a negative effect on FC effectiveness, everything that has happened to my water falls into place.
CYA levels have been around 50 ppm from the start. This level of CYA made my shocking doses inadequately low (beside the fact that they were not carried out properly). This in turn means that my CC would accumulate slowly. As frustratedpoolmom says, the supposed shocking has raised FC levels high enough to lower CC levels at times but that would only postpone the inevitable.
Add to that the pool cover that I started using about a week or two ago, which also apparently prevents CC levels from going down.

Putting all this together - a pool that's not chlorinated properly and that was just waiting for the CC levels to break sanitation altogether and bring about my green water.

I like it. Finally there is a variable that increases over time until it tips the balance.
Now the only question is whether the basic assumption is real or not.
Can anyone comment on the effect of CC levels on FC effectiveness if any?

 

[chem geek]

Can anyone comment on the effect of CC levels on FC effectiveness if any?

That's not it unless the FC test is getting "fooled" by something that isn't really FC (i.e. either unbound chlorine or chlorine bound to CYA). As long as you are measuring FC, it is still effective even in the presence of CC. It is CYA that makes FC less effective. There may be other CYA-like substances in the water that we are not aware of that could result in lower active chlorine levels (though this is unlikely in most residential pools), but CC is separate and not affecting the chlorine other than being something else in the water that chlorine can react with usually over periods of hours. Now CC can be an indicator for other things in the water, such as nascent algae growth, and if the FC/CYA ratio is too low then such algae can grow faster than chlorine can kill it and this can happen in areas of poor circulation even though the FC/CYA ratio seems to be OK in the rest of the pool water.

 

[Yoav]

Thanks Richard.

Thought it was a long shot....
I guess I will have to give it a rest, and start over.