Intek 15' x 48" - water is clear, but pool liner now looks greenish instead of blue

Hi,

I setup my Intek 15' x 48" pool on Tuesday (4 days ago). I followed the great advice in this forum and appear to have my pool in good shape (chemical levels provided below), but the pool water has gone from crystal clear and very "blue" to having a slight greenish tint (still very clear). By greenish tint, I mean when you look through the water to the other side of the pool, the liner looks greenish instead of blue (as it did a few days ago). Why the change? Do I need to add some shock or something else? I look forward to any suggestions.

Measurements taken this evening using hth 6-way test kit:

Cl ~ 5
pH ~ 7.5
Alkalinity ~ 80ppm
CYA ~ 50ppm
Hardness Test --> after adding 5 drops of indicator, water did not turn red, turned very light pink. After 2 drops of titrant, water turned very light green (not blue as test describes). Pool water came from town water supply, not a well.

I ordered the Taylor test kit that is recommended, but still waiting for it to arrive. Are there any other measurements I need to provide? I look forward to your advice. Not sure if I have a problem or not, maybe everything is still good, just wanted to make sure and be proactive instead of getting into trouble with my pool water. FYI - the light greenish look to the liner is not algae, it is just how it appears when looking through the clear water.

Thanks!

Kevin

What have you been using as a source of chlorine? Give us the ingredients. Also, how did you introduce CYA into the water? Did you add it separately or through a stabilized form of chlorine?

Also, I'd like to also ask you to fill out our Pool Chart with info about your pool.

Pool Chart Entry Form
Pool Chart Results

Welcome to the Pool Forum, by the way!

Hi Watermom and thank you for your reply. This forum is an amazing source of information and very helpful.

I introduced CYA using 2lbs of hth Stabilizer & Conditioner (96% Cyanuric Acid, 4% inert ingredients). Per recommendation on this forum, I added this into a sock and hung above the filter pump outlet jet to slowly disperse. It took about 2 days to completely dissolve into the pool. My source of chlorine is bleach (6% chlorine).

Please note that I completed the Pool Chart Entry Form as well and saw my entry in the Pool Chart Results page.

Please let me know if you need any additional information. Is is possible that some of the chemicals used changed/faded the pool liner pattern color? Just an ignorant idea...

Thank you.

Kevin

Did your chlorine ever drop really low? Does the liner feel slippery? This evening after the sun is off the pool, test your chlorine level. Then, add enough bleach to get it up to shock level of 15ppm. In the morning within two hours of sunrise, test it again and let's see if you are losing chlorine overnight. Report back if you lost any and if so, how much. (In your pool, each quart of 6% bleach will add about 3.3 ppm of chlorine. Use that as a reference to help you figure out how much bleach to add.

Your kit will only test chlorine levels to 5ppm, but you can force it to read higher by using a dilution method. Take one part pool water and mix it with one part distilled water, test and multiply the result by 2. If you need to go higher, take one part pool water and two parts distilled and multiply by 3. You do lose some accuracy with each dilution, but it is better than nothing.

One other thing to check, look inside the tank of your toilet. Are there iron stains in it?
Regarding the fading --- unless you have had extremely high chlorine levels, I doubt that this is the problem.

Thank you for the reply, Watermom. There are no iron stains inside my toilet tanks. Also, I do not recall my chlorine levels ever dropping low after adding in the bleach - I am taking measurements every morning and evening (the only time they were low was in in very beginning/first day or so when I was first adding the bleach to get the chlorine levels up).

Quick question - how long will it take for the chlorine level to drop after shocking it up so high? Can my kids (ages 6 and 8) still swim in the pool tomorrow if I shock it tonight? Just want to be safe with my kids and understand the expected timeline before they can swim after shocking the water.

Thanks!

Kevin

They can swim. Chlorine at 15ppm with a CYA of 50 won't hurt people, but it may fade swimwear so have them wear an old suit. Take a minute and read the Best Guess Chlorine Chart in my signature below.

Report back in the morning with your overnight chlorine loss and also how your water looks.

Hi Watermom,

I have definitely shocked the pool - I added ~ 4 qts of bleach last night and now my chlorine levels are above 15 (I diluted my pool water with 1 part pool water, 2 parts distilled water and it measures at least 5, maybe a little darker. Multiplying by 3 gives > 15). I also noticed that pH sky-rocketed as well. It is now > 8.2 (previously was steady at 7.5). Does the excessive bleach/chlorine of the chock treatment also increase pH levels?

One additional fact I forgot about is that I added 12oz of hth "metal control" after filling my pool with water (before adding any other chemicals). I had read online that this should be the first step in the water treatment process. Could this be the cause/source of the light greenish tint to my water?

After further review of my pool & water, I realize the the light greenish tint is in the water, not on the liner. NOTE: It is still present after the shock treatment. If I change the angle at which I look through the water, the "blue/green line" I see along the side of my pool "changes its location." It must have something to do with the pool water chemistry that is causing the light greenish tint to my water (still very clear). Could it be caused by the "metal control" that I added??? If so, is there a way to reverse the effect, i.e. drain some water and add new water? If so, how much should be drained? Or is this something I just need to accept for this season?

I look forward to your response. Hopefully my Taylor kit arrives soon so that I can get more accurate measurements.

One last question/concern - do I need to be proactive to reduce my elevated pH level? Should I take action to lower it or will it lower on its own as the chlorine level drops?

Thank you in advance for all of your support.

Kevin

Don't trust your pH reading taken while the pool had high chlorine. it will typically read falsely high. Wait until the chlorine drops below 5ppm and then recheck pH.

Why did you add the metal control initially. Do you think you have metals in the fill water? Why don't you do a bucket test to check for metals.

When testing for metals, you'll need the following:

(2) white 5 gallon buckets.
A 1 gallon or 1/2 gallon clean milk jug or orange juice container (to measure with) OR
A household scale accurate to within 1 lb.
A *fresh* jug (96 oz or 1 gallon) of plain 6% household bleach.
A box of 20 Mule Team borax.
An OTO testkit, like the Taylor 1000 or the HTH 6-way drops kit. (Test kit info page)
Lids or towels you can use to cover the buckets.
A plastic or stainless steel tablespoon measure
A plastic or stainless steel 1/4 cup measure
A clean household long-handled stainless or plastic cooking spoon.

To carry out the test:

Use the gallon or half gallon measure to collect pool water.
Fill the first white bucket with 4 gallons of POOL water.
(Measure by adding 4 measured gallons OR by adding 33 lbs of water to the buckets)
Fill the second white bucket with 4 gallons of FILL water, from whatever source is used to fill the pool.
To each bucket, add 1/2 cup of bleach & mix (~80 gal bleach /10K gal pool -- 480 ppm)
Mix completely with the spoon
Wait 15 minutes, and note any color change.
To each bucket, add 1/2 cup of borax,
Mix with the spoon till dissolved completely
Cover with lid or towel.
After 24 hours, inspect. Note clarity, color and sediment, if any visible
After 24 *more* hours, inspect. Note clarity, color and sediment, if any visible
Test both buckets for chlorine levels with OTO. You should not get a 'normal' reading, but report resultant color.
Report results.
Recover the buckets, and wait 3 days, and check again.

Thank you for the instructions. I need to go to store later today to pick up some of these required items and will start the test tomorrow. I will report back once I start getting results to report.

Kevin

Hi Watermom,

I started the test process tonight. After adding/mixing the 1/2 cup of bleach to both test buckets and waiting 15 minutes, the water color in the white 5-gallon buckets of both the hose water (used to fill pool) and the actual pool water both have a similar slight green tint to them. There were no green colored items in the nearby area where I am conducting the tests to give the green tint to the water. Please note that both water samples seemed to have a slight green tint even before adding the bleach, however, i could not tell if the greenish tint got stronger or not after adding the bleach. It is a very faint tint, so it is difficult to compare/contrast.

I will report back again tomorrow night after 24 hours. I just added the 1/3 cup of Borax to each and mixed it in. It was difficult to get it to completely dissolve in the hose water because it was cold.

Kevin

Hi Watermom,

I just checked both buckets after the first 24 hour period. Listed below are is the info for each sample:

Pool Water:
clarity = clear
color = very light green tint
sediment = noticed 4-5 very small black specs, size of sand grain (not sure if these are new)

Hose/Source Water:
clarity = clear
color = very light green tint
sediment = noticed 4-5 very small black specs, size of sand grain (not sure if these are new) as well as one larger black clump, maybe size of pencil eraser. I do not remember seeing this before...

I will report back again tomorrow night. Do you want Chlorine levels tonight? Please note that I just received my Taylor test kit in the mail today, so I now have a more accurate test kit.

Kevin

If you'll go ahead and measure your chlorine this evening after the sun is off the pool, and measure it again in the morning before the sun hits the pool, we can rule out or confirm algae or something else consuming your chlorine, by comparing the two readings. If you'll use the 10 mL sample instead of the 25 mL sample, and multiply your drops x 0.5, you'll make your reagents last longer.

Janet

Hi Janet,

I measured the chlorine level earlier this evening in my pool using the Taylor kit. The chlorine level measured at 11ppm. I did use the 10mL water sample in order to conserve the reagents - thanks for the recommendation.

I will measure again in the morning and report back.

I am definitely thinking it is not algae and something in the water chemistry, maybe some metals or something else in the water composition that gives a green tint. The pool liner and water is clear, but there is a green tint to the water when you look at it through natural lighting. It is definitely not green on the pool lining, it is the effect is light passing through the water that makes it have the light greenish tint as you look into the depth of the water. It is still sparkling clear, just with a green tint as light passes through the water. It was not this way on day 1 after setting up and filling the pool.

Kevin

Hi Janet,

Per your request, I measured the chlorine level again this morning. It measured at 10ppm (20 drops in the 10mL sample). Please note that I have not added any new bleach into the pool water since shocking it on Sunday night.

Kevin

I don't think it is algae. Doing the overnight test pretty much confirmed that. Looks like you have some metal in there. Kind of odd with city water. I've asked Ben or Marie (our metals guru) to take a look at your thread.

When you drain or lower your water level is there a change in the color of the liner or bucket? If not, then the color is in the water. Do you have copper pipes? It seems to me that the water is tinted when it comes out of your spigots, the slight greenish tint sounds like it may have some copper in it. You can find out if there is copper in your township water. If the water is tinted, I don't think it will be a problem. Do you know if anyone else in your area has the same problem? This is a tricky one since it is the same color in the bucket with your fill water. Please post and let me know,

Marie

I have seen green water from organically chelated iron -- that is, iron that was eroded from old iron or steel pipes by bacterial growth. These chelants (sideraphores) are apparently much stronger than anything you can buy commercially, and chlorine stable as well.

Your city is certainly old enough to have areas that will experience this problem, but you'd have to call your water company. You could also ask, in the same call, if they are adding anything to the water that would give it a greenish tint.

If you would, add another dose of bleach to both buckets. I'd assumed that the dose given was enough to break any chelant, but now I'm not so sure. I can't find anything on the oxidative destruction of sideraphores, and I don't understand the chemistry well enough to have any sort of educated intuition about it.

In the pool where I experienced this most notably, it would take up to 3 weeks for the greenish color of chelated iron to disappear.

Hi,

I just checked both buckets again after the second 24 hour period (total 48 hour so far). Listed below are is the info for each sample - no changes in status of water color, clarity and sediment, still the same:

Pool Water:
clarity = clear
color = very light green tint
sediment = noticed 4-5 very small black specs, size of sand grain (not sure if these are new)

Hose/Source Water:
clarity = clear
color = very light green tint
sediment = noticed 4-5 very small black specs, size of sand grain (not sure if these are new) as well as one larger black clump, maybe size of pencil eraser. I do not remember seeing this before...

I also measured the chlorine levels in both buckets, too. Interestingly (to me at least) was the chlorine levels in the hose water is higher than that from the pool sample. The pool water sample measured 22ppm CL while the hose water measured 28ppm CL. Both samples has 1/2 cup of bleach added to them 48 hours ago, but the pool water has previously been shocked, too (so it was starting with an already high CL level). Does this make sense? The pool water also has additional pH and CYA modifications which had not been done to the hose water.

Is it still worth me adding another does of 1/2 cup bleach to each bucket per Ben's recommendation? I imagine this would put the CL levels ridiculously high (will use up most of my reagent to measure CL levels ;-) ).

Ben - please let me know if think I should still add another 1/2 cup bleach to each bucket.

Marie - the water pipes in my house are copper. For reference, my house was built in the early 60's.

As long as the greenish water is "safe" for my kids, which I assume is the case, I am fine with it. It is still very clear, just has a greenish tint to it. If there was a way to clear this up, I am open to it, but I do not want to have to do something too drastic if the water is fine with the slight greenish tint. Doe the Taylor kit have the ability to measure for copper or iron in water? I have not read through the guide that came with it, so I am not sure of all of the tests available in this kit.

I will also try to call my town hall to see if they have any information about the green tint to the water. If I learn anything, I will report back. Last week I just received our town's annual report on water quality, the values tested and provided in the report are lead, barium, mono-chloramine, fluoride, nitrate, nitrite, perchlorate, total trihalomethanes and haloacetic acids-5. Are any of these helpful?

Thanks again for all of your help.

Kevin