Help, Pool Water is Green!

[Michelle9]

Help! We came home today and pool water was light green, it is still clear and you can see the bottom of the pool easily. We have had great numbers all week and crystal clear water. Kids and adults have been swimming everyday this week.
It rained last night and today. Tonight numbers are

FC 2.5
CC 0
pH 8
TA 270 (haven't tested this for a while)
CYA 20-30 (we have differing opinions) added CYA last week, plan to add more.

I know I need to lower the pH, will buy muriatic acid this week, it looks like by lowering pH TA will come down. It just started to rain again and I think it will rain all night. I did add 1/4 gallon of bleach tonight.


I am a little disappointed as I really thought I had this pool water testing down. I have been testing the FC, CC, and pH regularly, but not the TA and CYA. Please let us know what we need to do. Thanks so much.

 

[tim5055]

Get the pH down first. I have a hunch the high pH has allowed some copper to precipitate out. Have you used algecides in the past, do you /did yo have a pool heater or maybe di you use some sort of mineral system (Nature2) before finding TFP?

Clear green water is many times metals in the water rather than algae.

 

[Michelle9]

At the beginning of the season, when our pool was black green, my husband went to the pool store. He had talked to some friends at work with pools and was going to get it ready for the season. He did put powdered chlorine and 96oz of liquid algaecide. We don't have a pool heater and don't have or know what a mineral system is. When the pool store plan did not work I started back on this forum and did a SLAM and the pool water has been beautiful until today.

 

[Richard320]

Sickly green is usually iron. Brilliant Emerald green is copper. Cloudy green is algae, especially if the walls feel slimy too. Most likely the aeration from the rain drove the pH up so the metal is precipitating out. Lowering pH should help. If not, post back.

 

[pooldv]

With TA that high you need to keep a closer eye on your PH. High TA will drive your PH up faster. When PH gets to 7.8 add acid to lower it to 7.2 and this will slowly lower your TA.

 

[domct203]

If your CYA is 30 you should target FC at 4ppm. 2ppm would be the absolute minimum.

As mentioned get that pH down ASAP.



Dom

 

[Michelle9]

OK

Thanks for the advice. Yesterday evening pool was green and I would say it was bright green, today pool is less green maybe there is a green tinge but there is blue too, still clear, we added Muriatic acid this morning.

Reading now is

FC 3.5
CC 0
pH 8

Can I add more acid today? Is it like bleach during slam, or how often do I check the pH and how often can I add more acid.

Thanks

Micchelle

 

[Richard320]

Yes, add more acid. You were probably off the top of the scale somewhere. It may take two or three doses to get pH into range. Just allow thirty minutes with the pump on to let it mix before you test and another thirty minutes with the pump on after you add acid so it dissipates.

 

[Michelle9]

Thanks we added more and now we are at 7.2!

 

[tim5055]

Thanks we added more and now we are at 7.2!

Is the green going away?

 

[Scuba_Steve]

Contrary to the advise given above, I would go lower. Ta is lowered by adding Muriatic Acid. This is more effective at lower levels of pH. 6.8 is the bare minimum you should go. 7.0 is safer. I would wait for the pool to raise itself to 7.4. Then lower it back down to 7.0. Wait for 7.4 and repeat. And when I say repeat, repeat this over and over and over. It takes a long time because your only loosing a few ppm of TA every time. Keep going until you are between 60-80 TA.

- - - Updated - - -

Going from 7.8 to 7.2 and back will work as well. It will just take longer doing it this way. PH slows down as it gets higher. Keeping it low will allow it to raise much quicker.

 

[Michelle9]

There is a dull greenish hue, better than last night. Just had a thought we do add water to our pool when it needs it and we are on a well. Last year the pool was filled with pool water, but when the level starts to get low we fill it from the hose. It is not too often, but maybe that is where the metal/green came from. But up until tomorrow ever since we completed our slam the pool water has been blue, clear and sparkly. Here it is today
http://im1.shutterfly.com/media/47a5d828b3127ccee9074e17542800000040O00CZNmbRw4btQe3nwo/cC/f%3D0/ls%3D00507884360220150610010004431.JPG/ps%3D50/r%3D0/rx%3D720/ry%3D480/

 

[Michelle9]

http://share.shutterfly.com/action/welcome?sid=0CZNmbRw4btWEi

This is how it has been looking

 

[Michelle9]

OK appreciate the advice. Read up on TA some more too. I will retest pH and TA and see where we are. I understand to lower pH to 7.0 with acid, leave the filter on to aerate the pool, which will bring the pH up but not the TA, If TA still not down, then add more acid to lower pH, aerate the pool, test again. Continue to repeat process until TA is 60-80.

 

[JoyfulNoise]

You should check your well water. Since you're in IN it could be a source of very high TA if it comes from a deep well.

Do you have a municipal water supplier in your county? If so, sometimes they test residential wells for free or they can point you towards a reputable lab for testing.


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[JoyfulNoise]

Contrary to the advise given above, I would go lower. Ta is lowered by adding Muriatic Acid. This is more effective at lower levels of pH. 6.8 is the bare minimum you should go. 7.0 is safer. I would wait for the pool to raise itself to 7.4. Then lower it back down to 7.0. Wait for 7.4 and repeat. And when I say repeat, repeat this over and over and over. It takes a long time because your only loosing a few ppm of TA every time. Keep going until you are between 60-80 TA.

- - - Updated - - -

Going from 7.8 to 7.2 and back will work as well. It will just take longer doing it this way. PH slows down as it gets higher. Keeping it low will allow it to raise much quicker.

For general awareness, I think you need to qualify your statement by saying that going lower to 6.8-7.0 is MAYBE ok for vinyl pools. For many plaster surfaces, a pH that low could easily drive the CSI below -0.6 which would put plaster pool surfaces in danger of etching. Remember that the pH scale is logarithmic and so going from 7.8 to 7.6 is a lot easier (less acid) than going from 7.4 to 7.2. As well, the CSI is logarithmic and you need to pay close attention to that number if you plan to operate a pool outside the TFP recommended levels.



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[Michelle9]

Thanks so much.

I will find out about getting our well water tested.

Just now:

FC 3
CC 0
pH 7.4
TA 225

Will add muriatic acid.

Michelle

 

[Richard320]

I'm lost.

Is the green gone?

Why are we worrying about TA? I haven't seen a CH reading anywhere, so we have no idea if she's at risk of scaling. The pH is good now, if it doesn't hold for more than a few days at a time and she's sick of adding acid, then worry. The fact is, it will take the same amount of acid to lower the TA whether it's forced and lowered in a weekend or brought down over a few weeks. I say less fussing and more swimming.

To quote from the Pool School article

There are two reasons to lower your total alkalinity (TA) right away, because you want to slow down the rate that the PH rises, or if high TA is contributing to a high calcium saturation index (CSI) which puts you at risk of calcium scaling. You shouldn't lower TA just to reach a target number. Make sure you actually have one of the above issues before lowering your TA.
emphasis added​

 

[Scuba_Steve]

Yes I agree. Other do read this. I guess I had tunnel vision and was only focusing on the OP, who has an AG pool.

 

[Scuba_Steve]

I'm lost.

Is the green gone?

Why are we worrying about TA? I haven't seen a CH reading anywhere, so we have no idea if she's at risk of scaling. The pH is good now, if it doesn't hold for more than a few days at a time and she's sick of adding acid, then worry. The fact is, it will take the same amount of acid to lower the TA whether it's forced and lowered in a weekend or brought down over a few weeks. I say less fussing and more swimming.

To quote from the Pool School article

There are two reasons to lower your total alkalinity (TA) right away, because you want to slow down the rate that the PH rises, or if high TA is contributing to a high calcium saturation index (CSI) which puts you at risk of calcium scaling. You shouldn't lower TA just to reach a target number. Make sure you actually have one of the above issues before lowering your TA.
emphasis added​

Correct me if I am wrong Richard. I am new to this and very well could be.

Most solutions will at some point come to a resting point pH wise. This meaning that it will take an unusual amount of outside force to cause it to raise any further or in the other extreme lower further. A "normal" swimming pool has this resting point around 8.2-8.3 from what I understand. After that you can aerate away and it will not budge.

The OP had a pH high enough that it was off the scale. Not only off the scale, but off the scale by quite a bit from how it sounded. Also more than likely due to pH issues the pool was precipitating metals.

I therefore made the conclusion that the OP had a pH problem that needed a more long term solution. That is why I suggested to fairly aggressively attack the very abnormally high TA.