copper green tint to the water?

[bajadudes]

when I first filled my pool from my well at the beginning of this season the water looked fine until I added liquid chlorine and the water turned green. My PH was also high but I don't remember exactly what it was since I had an el cheapo 2 tube shake n bake chlorine and PH kit. I read everything in the pool school and scoured this great site. I went out and bought more liquid cHlorine, Borax and baking soda and proceeded to fiddle with PH. At some point I did something and within 15 min the green simply vanished like magic. I counted my blessings and promptly purchased the TF100 test kit. All has been perfect for the entire season until about 2 weeks ago. I was away and for reasons that are to long to elaborate the PH went way up and chlorine went to zero. Since then I have been struggling to get it back to crystal clean from the green tint it now is.

The water does appear to be a bit hazy but there is no slimy feel to it or any of the surfaces on the vinyl. This green has the same look and quality of that original green I described earlier. 3-4 days ago I finally managed to get the PH and TA in good range. I have added water over the summer a few times, each time when it was down about 2 - 3 inches. 3 days ago CYA was 35 so I added about 2.5 Lbs to hopefully bring it up around 60. I figured I should get PH right before really shocking.

three days ago the numbers were:
FC 2.5
cc .5
TC 3.0
PH 7.8
TA 90
CYA 35

Added muriatic acid and cyanuric acid and bleach over the next 24 hours

yesterday

FC 14.5
CC .5
TC 15
PH 7.0
TA 90
CYA 50

Added 4.5 gallons chlorine and 4.6 Lbs baking soda during the course of the evening. baking soda 1st then bleach 4 hours later.

today

FC 36
cc 0
TC 36
PH 7.5
CYA 55

PH crept up so I added about 26 oz muriatic acid

It has been about 5 hours with no noticeable difference whatsoever in color.

I really think this is copper at this point. Is it possible that the 1st time I got rid of the color so magically that it was because I went too low on the PH. I seem to recall using Borax to bring it up at some point. I wish I would have taken note of what I did back then.

Will a low PH sequester copper? Is it possible to turn water green by adding bleach?

The green now seems to be different from the initial green of a week or two ago. maybe I killed off the algae but now am left with this same green issue I had at the beginning of the summer.

I have been back washing but it is not unusually frequent.

Any thoughts or help would be appreciated

 

[bajadudes]

OK I am going to do an overnight chlorine loss test and see what that shows. I think i have over fiddled with chemicals and with FC so high my PH tests are worthless.

Thanks for this great resource and letting me think out loud.

 

[duraleigh]

Welcome to the forum. :lol: Your initial fill green issue sounds very familiar. The past two Springs, the initial introduction of chlorine into my pool (from well water) has turned the pool clear green within 20 minutes or so. That green has remained in the pool for about 3-5 days and then slowly disappeared.....I did nothing but let the chlorine drop of it's own accord.

Tests for iron and copper in my water yields absolute zero.

I, too, think this is related to pH and SOMETHING in the water but I sure wish I could test and get at least a trace of copper from my well but I don't.

If your pool is like mine, it is VERY clearly not algae, and it is not repeatable for me as subsequent shocking of the pool with high FC does not have any affect.

Next Spring, I plan to do a very controlled set of testing and FC application in hopes it will repeat and, with the help of some folks smarter than me, we will be able to discover what causes this.

Lastly, I never needed to backwash either and while my green didn't disappear in fifteen minutes, I didn't apply any chemistry at all so mine simply faded away over about a three day period.

 

[linen]

Welcome to tfp, bajadudes

OK I am going to do an overnight chlorine loss test and see what that shows. I think i have over fiddled with chemicals and with FC so high my PH tests are worthless.

You posted while I was in the process of responding...but you are on the right track Do the OCLT to eliminate (or prove) that this is algae and don't mess with ph until your FC is below 10 ppm since the test will read high. Even if you do not pass the OCLT, it might be a good idea to let the FC drop down briefly to 10 ppm so that you can retest ph and adjust before starting the shocking process. If you have lowered ph while being at a FC over 10 ppm, it is possible that your ph is really low right now and if you have a copper tubed heater, then you could be getting more copper from that. If you fail any of the three criteria in the shocking process make sure you continue the process until you pass all three criteria listed in that pool school document.

 

[bajadudes]

Thank you for the encouragement and sharing. I will report results as they are obtained.

Initial PH work was done with chlorine levels very low to non existent. My thinking was to do that first before shocking. In my exuberance and subsequent loss of patience I continued to fiddle with PH over the last 3 days when shocking and ignored the sensible voice in the back of my head.

No heater or other copper tubing so that can't be a copper source.

Thanks again.

 

[bajadudes]

I just realized I may have made a critical error in determining FC.......the past 3 times ( figures in my original post ) I did not multiply the number of drops by .5.....Duh

I cannot be certain I am reaching the correct shock number as per my CYA of about 55-60.

Right now FC, an hour after sundown stands at 13.5. I will see what it says in the AM in order to see what if any loss I have.

Question 1) should I let FC drop down to about 2-3 and make sure I have correct PH before shocking to correct level?

Question 2) When you do chlorine drop test with the FT100 you are supposed to count the number of drops for the solution to go clear. Ok this is subjective but in the case above drop # 26 turned it just about clear but if you looked at it carefully there was still a very very faint pink to the color. drop # 27 made it perfectly clear. So which value do i go with drop # 26 or 27? Above I went with #27.

 

[linen]

Question 1) should I let FC drop down to about 2-3 and make sure I have correct PH before shocking to correct level?

As long as FC is below 10 ppm (i.e. 20 drops of the R-0871), you can trust the ph measurement.

Question 2) When you do chlorine drop test with the FT100 you are supposed to count the number of drops for the solution to go clear. Ok this is subjective but in the case above drop # 26 turned it just about clear but if you looked at it carefully there was still a very very faint pink to the color. drop # 27 made it perfectly clear. So which value do i go with drop # 26 or 27? Above I went with #27.

Add drops until the last one makes no difference from the previous drop, then subtract that last drop. So if you added 26 and it became clearer, then added 27 and it became even more clear, but when you added 28 it did not change from 27, then your number is 27/2= 13.5 ppm FC.

 

[bajadudes]

Thank you linen for taking the time to respond, much appreciated.

 

[bajadudes]

This morning FC was 12. It dropped 1.5.

What do you guys think?

check again tonight when it should be below 10, adjust PH and then do a real shock?

Question, does chlorine not evaporate out under normal circumstances even in the evening? Weather in Raleigh NC last night no wind, about 73 degrees and it's a 24 ft round above ground pool. Water temp 78 degrees.

Water looks about the same.....no change

 

[duraleigh]

Two things consume chlorine.....sunlight and organics in the pool water. You eliminated the sunlight so you have organics. I still don't think you have enough to turn your water green but you may as well shock and clear that up although I think the shock process is going to extend the duration of your green color as it will make the pH somewhat higher.

If It were my pool, I would hold FC around 6-8ppm constantly for the next couple of days or more and then do an OCLT somewhere around day three to see if that elevated chlorine got rid of the organics. At the same time, I would drop pH down to around 7.2 and see if the green didn't go away.

Do you have a pic?

I am suggesting sort of an inbetween approach because of what I think to be metals in your water. The shock process is certainly a viable option as well.

 

[bajadudes]

If It were my pool, I would hold FC around 6-8ppm constantly for the next couple of days or more and then do an OCLT somewhere around day three to see if that elevated chlorine got rid of the organics. At the same time, I would drop pH down to around 7.2 and see if the green didn't go away.

Do you have a pic?

I am suggesting sort of an inbetween approach because of what I think to be metals in your water. The shock process is certainly a viable option as well.

I will take a picture tomorrow, I was working all day sorry. So hold to the 6-8 ppm FC for about 3 days even though CYA is around 55 - 60?

Tonight's reading after the sun went down were:

PH = 7.2
FC = 7.5
CC = 1 ( it was barely, ever so slightly pink after the 1st drop and the 2nd made it completely clear)
TA = 90

So it looks like during the day chlorine dropped 4.5ppm
CC went up .5 from the previous evening.
and TA dropped by 10 since the previous evening.

PH looks good so I am not going to touch it
Will check FC tomorrow AM before sun-up
What about TA should I bring that back up to 110 with 4.6Lbs of baking soda as pool pal says? Maybe go slow and do 3 Lbs?

Pool still looks green.

Thanks everyone for their input and advice.

 

[bajadudes]

This morning

FC 7.5
PH 7.2

Still wondering if I should do anything about TA as stated in previous post

 

[duraleigh]

Leave your TA alone. Look at the acceptable parameters up in Pool School ("The ABC's of Pool Water Chemistry")

It appears you have never been outside those parameters so there is no need to adjust.

 

[bajadudes]

Duraleigh, thank you again for your input. The only reason I mention the TA is because the TF 100 test kit says that the ideal TA for a normal pool ( not salt water ) is between 100 - 120. the pool school specs seem to be more liberal.

The pool is still the same green and I am sorry i have not been home during daylight hours to take a good picture. I have been using the 3rd step down into the pool on the ladder as a rough guide and it seems that visibility is about the same, i.e I can't see the step below it.

Tonight's numbers after adding approx 76 oz of 6% bleach this AM are:

FC=9ppm
cloramides= .5
PH steady @ 7.2

Will report the AM numbers when I have them.

Any insights based on the past few days are always appreciated.

 

[onBalance]

If water is clear to begin with, and chlorine bleach is added and the water turns green within minutes, then iron is likely. Also, once iron has been oxidized by chlorine and precipitates, it may not show up in tests, because it is no longer soluble. If the water has been very acidic for a while, and then add an alkaline product like soda ash which raises the pH (even chlorine bleach raises the pH initially), the water may turn a turquoise color from a high copper content. You should be able to tell the difference from a tint green color. Based on the information above and the fact that the TA is not low, it probably isn't a copper problem, but more likely a iron issue. I base that on you stating that the chlorine level went to zero for a while, and I am guessing that you may have added some more well water, and then added chlorine, and the water turned green again.

The water can also turn a slightly tint green color from the lack of proper filtering. There may be matter in the air that is blowing in, and either the filter is not running sufficient hours, the pump is not moving the water, or the filter is dirty, etc. Since you have a sand filter, I suggest you also try (along with the other advice) adding 2 cups of either DE or Fiberclear to the skimmer and run the filter 24/7 and watch the pressure gauge. That will help remove iron or particulate matter.

 

[bajadudes]

Thank you for your insight, it is greatly appreciated. I have added well water over the summer whenever the level was down, maybe 10 inches over the summer in a 54" pool. When the pool "got away from me" the PH was very high and chlorine near zero and color was a turquoise-ish green but also murky/cloudy. The filter has been running about 10 hours per day and i have back-washed 2x in the past 2 weeks.

I have considered adding DE and now think I am definitely going to do it. Tomorrow will be the 3rd day of the suggested therapy after which I am uncertain if I should try a "real" super chlorination based on the CTA table or try to use a metal sequestration additive.

Tonight there are heavy rains in my area so I will backwash tomorrow and drop the level a bit.

I should have never let it get away from..lesson learned the hard way. Then again if you are not making mistakes you are not learning anything.

 

[linen]

I have considered adding DE and now think I am definitely going to do it. Tomorrow will be the 3rd day of the suggested therapy after which I am uncertain if I should try a "real" super chlorination based on the CTA table or try to use a metal sequestration additive.

Is the water clear now with just tinting, or is it cloudy? If its cloudy, do the shocking process, if clear then I would try Onbalances DE suggestion, and if that does not work, then a sequestrant may be needed.

 

[chem geek]

The only reason I mention the TA is because the TF 100 test kit says that the ideal TA for a normal pool ( not salt water ) is between 100 - 120. the pool school specs seem to be more liberal.

If that's the case, then the TF-100 instructions are wrong and should be changed. Higher TA is only normally used with acidic sources of chlorine such as Trichlor.

 

[bajadudes]

I just double checked and that is indeed what the TF 100 instructions say regarding TA.

This mornings numbers are

FC 7

PH with the overnight rain has crept up to somewhere between 7.2 and 7.5.

Tonight I will do a super clorination based on a CYA of 55 and go an extra gallon for good measure. I will maintain that level for 3 days and see what happens. Does this seem like a sound approach?

 

[duraleigh]

Tonight I will do a super clorination based on a CYA of 55 and go an extra gallon for good measure. I will maintain that level for 3 days and see what happens. Does this seem like a sound approach?

Yes, it does. It has been difficult to tell whether you have metals in your water, algae or both. Do you have that picture(s)?

Murky green is usually algae and clear green is almost always metal. At this point in your narration, it sounds more and more like algae may be the issue. Don't "super chlorinate" but rather follow the shock process as described in Pool School. You should see a daily improvement in the color of your water.