My new plaster pool is COVERED in green stain..

[hausfrau]

This is very scary. New white plaster pool. Pool filled with 1/4 of our wellwater (Texas Hill Country) and two truckloads of water from local water company. Pool is about 3 weeks now. I will give all details even though they may not have anything to do with how this happened:

Purchased new chlorine tabs at Home Depot: they were different from what our pool company had given us (blue specks imbeded in them...a filler) thought this might be the problem so took these back and got 100% pure chlorine tabs.

Realized that chlorine was set at full blast on equipment dial (pool tech must have forgotten to tell us to turn it down) so lots of chlorine.

We've had to add meriatic acid a few times...at his advice as we are trying to get water levels to settle down.

Daughter had sleepover and many girls playing in pool over this weekend.

Sunday, pool started getting covered in what appears to be a dark green stain. Does not rub off AT ALL.

Stains are on bottom two stairs..bottom of pool (not as dark in shaded end but still there) seems to be about 6 inches from surface of pool and all over bottom.

Can actually see where one of the girls sat in the spa and on a step...this is puzzling.

I did read a post on metals in pool water and crushed vitamin C in a sock. IT WORKED ON THE STAIN WITH LOTS OF RUBBING.

I got this "metal out" product from pool store and according to directions for my size pool, (14000) etc added that to the pool last night.

This morning still the same.

My fear: could the gunnite be showing through or could this be a plaster problem? So scary when one has invested in an expensive pool and now it is not as it should be. The installer of the pool is very baffled. He has been installing pools out in these parts for over 10 years (well water) and has never seen this. Even he is very concerned. HELP!

Chrlorine is too high to have water tested yet. Waiting for it to go down.

[PoolDoc]

Dark green (greenish blue can be copper) is not a color I've seen, so I can only offer general advice.


Try to get your chlorine down -- if it's the pool tech's fault, ask him to lower it. High chlorine generally increases metal staining.
Don't bother with liquid metal control agents till the chlorine is down -- chlorine destroys them.
Ascorbic acid (vitamin C) is ALSO destroyed by chlorine.
Lower your pH as low as your plaster guy allows -- metal staining decreases as pH decreases.
Have your water tested for copper.
Find some other place to test, if you can -- a pool store that can't test for high chlorine probably can't test anything reliably.


You probably want to lower chlorine and pH ASAP. Stains tend to become harder to remove the longer they are in place. So, it may be pretty urgent to get chlorine and pH down NOW. A responsible pool tech should be willing to make extra trips to resolve a problem he helped create, even if it was an accident on his part.

Also, use polyquat as soon as you get your chlorine low. (High chlorine ALSO destroys polyquat!) And, then, keep your chlorine low, replacing chlorine with polyquat. I'd avoid non-family use for now.

Ben
"PoolDoc"

[hausfrau]

THANK YOU. I will do this and see what happens.

[Watermom]

Do you know what the name of those other tabs were? Did you read the ingredient label? Some trichlor pucks have copper in them. You NEVER want to buy those. I *think* they may be called dual acting or something like that.

[waterbear]

I did read a post on metals in pool water and crushed vitamin C in a sock. IT WORKED ON THE STAIN WITH LOTS OF RUBBING.



This is setting off warning bells for me. Vitamin C (ascorbic acid) works on metal stains by chemical action (reduction) and does not need rubbing!
Algae often needs a lot of rubbing to remove it.
Metal stains don't rub off unless you rub hard enough to removed plaster.

The other red flag is that the problem started after your daughter's sleep over, which very likely created a low chlorine condition in your pool! You also stated that the stains are not as dark in shaded areas of the pool. Algae needs sunlight, metal stains don't.

I suspect you are seeing green algae on fresh plaster.

Try holding a chlorine tablet on a stained area for about 10 minutes and report what happens. (wear rubber gloves or use something to hold it on the stain) If the stain lightens and/or disappears it is algae.

Please pose a full set of test results ASAP.
Chlorine too high to be tested and chlorine high enough to kill algae are sometimes not the same. It depends on some of your other readings and how you are testing the chlorine. With some water testing setups (even professional ones) chlorine that is too high to test can be chlorine over 3ppm, which is not very high at all and often not high enough to stop an algae outbreak .

[PoolDoc]

Good points, Waterbear.

PoolDoc

[waterbear]

Good points, Waterbear.

PoolDoc

thanks! :)

[hausfrau]

You are all so very helpful. Update: My husband drained down the spa and squired a solution of meriatic acid (10%) and water. Boom. Stain completely gone. A neighbor was able to gingerly rub at a dark smear on the side of the pool and he actually was able to remove the stain. This was using a stainless brush which I am not a fan of and have not used. So, this being said, my local pool store suggested we brush the pool (used nylon brush) and put in a solution called Supercide (algea destroyer and stain remover). Honestly, I don't see much difference. Algea may look a little lighter in some areas. Sometimes your eyes play tricks.

Here's the readout. 14000 gallon pool. temp 85 degrees, algecide level 0, Protector 28 N, total solids 1700, saturation index -0.4, free chlorine 8.0, total chlorine 8.0, alkalinity 45, calcium hardness 220, ph 7.4, stabilizer 100. They suggested low alkalinity and had me buy equalizer. Then, muriatic acid. This was tested on Friday of last week. it is now Monday. I will probably get it tested again tonight as I will be near the pool store.

[hausfrau]

The chlorine test I am using is a home strip that you dip into the water. I don't like it alot as the reading won't tell you how high the chlorine is...just that it is too high! it will be high right now because of last nights Supercide treatment...I turned off the chlorinator until it seems to level off.

Initially, our pool installer had the chlorine cranked all the way and I did not realize I was supposed to turn it down after a few days. Now that I know how to adjust the chlorine flow, I can better adjust that. Man, this is a pain. I never should have put in a pool ;0

[mbar]

You have algae, and the only way to get rid of it is by using high levels of chlorine until the chlorine holds within 1ppm overnight. With a cya of 100 you need a minimum of 8ppms, and to take the pool up to shock levels you will have to take your chlorine level up to 25ppms and keep it there testing every couple of hours to get it back up to 25. You may also want to do a partial drain and refill to get your cya between 30 and 50. You are wasting money on all the chemicals the pool store is selling you to kill algae that will die with high levels of plain old bleach ;). I would be very leery of the chlorine tabs with specs in them. Make sure they don't contain copper. You also don't want to use the chlorine tabs that are trichlor as they will raise your cya even more. You should take a look at the chlorine forums and the algae forums - you will see that good old fashioned bleach really does work. The best suggestion I have for you is to get a good test kit so you can test your own water and learn how to take care of your pool yourself and not be at the mercy of pool stores. Do a lot of reading on this site, and ask any questions you have. Everyone here loves to help:)

[hausfrau]

You are so nice.

I have actually asked about a more high tech kit for testing my water and was told there isn't really anything better than the strips I am using. Hmm...a plot here? I do not want to be at the mercy of the pool stores...I am a nice calm person, but I am getting rather riled up as each time I go in, I get a different opinion.. Iwas wondering...should I have my well water tested-the water that the pool is hooked up to?

I will take your suggestion...and thank you for it. I am going to take a pool class that Self-Chem offers...but will take some of it with a grain of salt (no pun intended) as they probably want us to be dependent on their chemicals! I am also brushing the plaster more right now in hopes that it will inhibit the growth too. We are having lots of storms now (near Austin, TX) so I am sure this will throw everything out of wack too.

Please wish me luck! I'll keep ya'll posted on my pool nightmare!

[waterbear]

You are so nice.

I have actually asked about a more high tech kit for testing my water and was told there isn't really anything better than the strips I am using. Hmm...a plot here?

As someone who has worked in pool stores I can tell you that the answer is probably yes. We did not carry decent test kits (except for the K-2005 we stocked in units of 1 for the condo associations) so people would come to us for water testing and we could sell them a lot of stuff!
As far as test kits, get yourself a Taylor K-2006 (not the K-2005). It will save you a lot of time and money in the long haul!
You might have to order it online. Here is a link for Amazon:
http://www.poolforum.com/pf2/showthread.php?t=10006
While this is not the only place you can get it you will be supporting Pool Forum by ordering from this link and help keep it going.

[hausfrau]

Just for the heck of it, I had our well water tested to check on metal in the water. it came back very low for copper...0.2. So yes, algea. Now, to get a decent test kit (as suggested on this site) and buy some bleach...will keep ya'll posted!

[hausfrau]

Thanks for the good advice!

Muriatic acid seems to have done the trick in our spa. We turned the spa off and added a muriatic to the water. Let it sit for an hour. It really cleaned it up. The concentration would have been about .2% for total volume.

A few questions:

1. What is the maximum concentration of mutriatic acid that can be safely used in a plaster pool? (14400 gal)

2. Can the PH be lowered a significant amount for a period of time then raised to normal levels without potential damage to the plaster?

3. Should the DE in the filter be changed or backwashed to eliminate any residual algea?

4. As an aside, to eliminate the possibility of metal staining, will muriatic acid also remove Cu or other metals from the surface of the pool?

Again thanks for the help. Big learning curve for us on this!

[hausfrau]

My earlier posts have been about the dark green algea all over the plaster of my NEW pool. After doing a test in the hot tub only...muriatic acid made it go away. Chlorine has not worked (old theads will give more detail), but no, it is not a metal stain... so

A few questions:

1. What is the maximum concentration of mutriatic acid that can be safely used in a plaster pool? (14400 gal)

2. Can the PH be lowered a significant amount for a period of time then raised to normal levels without potential damage to the plaster?

3. Should the DE in the filter be changed or backwashed to eliminate any residual algea?

4. As an aside, to eliminate the possibility of metal staining, will muriatic acid also remove Cu or other metals from the surface of the pool?

[hausfrau]

We added the muriatic acid to the water this time...rather than draining and spraying. It is snow white again.

[waterbear]

Muriatic acid is not killing the algae. it is removing a layer of plaster from your pool and that is not always a good thing.
Extended periods of pH below 7.0 are hard on pool equipment at best and outright damaging at worst.

If you have a heater I hope you bypassed it because heat exchangers are easily damaged by low pH. The result of damage to a heat exchanger is usually green hair and copper stains on the plaster--out of the frying pan and into the fire so to speak.

There are methods for doing a "no drain acid wash" which is what you have attempted but they include monitoring the pH and bringing the pH and TA back up once the treatment is finished. They should not be attempted unless you have both acid and base demand tests and access to the large amounts of baking soda, soda ash, and/or borax that is going to be needed to stop the process. Also, a pH testing method other than phenol red is a good idea so you know just how low the pH really is. Best choice is a calibrated pH meter (expensive piece of equipment).

While you may have removed the stain you have not killed the algae.
to answer your questions as you numbered them:

1. you do not want the pH below 7.2 for an extended period of time! Amount of acid that will lower the pH depends on your starting pH and TA so it is impossible to give a set amount.

2.In a word, no.

3. Algae is not going to be your problem now. You have probably elevated your calcium hardness at this point by dissolving plaster. Just clean the filter like you normally do.

4. Muriatic acid is used to remove metal stains when other methods fail. Certain copper stains (the black ones) are very difficult to remove and acid washing is often the only recourse. Realize that it removes the stain by removing a layer of plaster. You can only do this so often before you need to re-plaster the pool.

Also, acid washing is the only thing that can remove scale (calcium deposits). Realize that calcium is also a metal.

Finally, Muriatic acid does not kill algae, chlorine does. If you had a bit of patience and persistence you would have eliminated the problem without causing damage to your plaster.

Hope this is helpful and gives you something to think about.

[sunofthebeach]

do you have any of the"algae" left? Can you post a picture?

It is hard for me to believe your pool installer did not know what algae looks like.

I do like your style hausfrau, charge forward and try anything and everything.

If it were me I would go out today and get a test kit, even if it is a $5 chlorine and PH kit from Walmart. I have rough, pitted in some areas plaster because I did not pay enough attention to the PH and Calcium.

If what you really have is Algea, you are going about it wrong goofing with the muratic acid. I am sure acid will kill algea, but you probably harming something else.

[hausfrau]

Waterbear & sunofthebeach. Thanks for your posts. I should clarify. What killed the algea in the spa was not the acid but a shock to the spa. I isolated the spa from the pool and elevated the Cl enough to kill it then lowered the PH level to 6.5 for 4 hours. Not sure but I believe that the lower PH and short time period should not have attacked the plaster agressively. After the soak I purged the Spa. The spa feeds the pool. (500 gal into 14400 gal). I did not drain from the spa only from the pool so 6.5 PH water never touched the heater. Test strip shows Ca at normal levels for our water after 16 hours of circulation. Testing for Cu in both pool and supply show very low levels.

After the stain removal step. I circulated the pump for three days and the algea returned leading me to believe that a high sustained Cl level is needed to truly rid the pool of algea. As for the staining more than likely we will see what happens after a week or so. I purchased a test kit to get a better testing capability than the strips.

per an earlier post i read a sustained level of 25ppm is needed for shock levels. Any ideas on time period?

[aylad]

Maintain shock levels until the pool clears, the CC goes to less than 0.5, and you're not losing any chlorine when comparing test results from testing at sundown and again in the morning before sun hits the pool.

Janet

[hausfrau]

Did all of that. Honestly, we have tried it all. Still there...a little worse. Is it possible that minerals or something is leaching from the gunite that can cause stains which are almost impossible to remove? The pool's gunite cured during heavy pollen season. The pool is under trees. If the plaster folks did not wash out all of the pollen properly..could this be causing a problem?

[waterbear]

first lets get down to basics....
How are you testing your water?

If, as you say you have "Honestly, we have tried it all." and it is "Still there...a little worse." THEN
I can honestly say that you are trying to adjust your chemicals with imprecise test results or you are just "dumping and guessing". Which is it?

Killing algae is easy if you know the CYA. Raise the FC to the proper level as in this chart
http://www.poolforum.com/pf2/showpost.php?p=1750&postcount=1
You need to maintain the FC at the proper shock level or a bit above by testing the FC and adding more UNSTABILIZED chlorine at least twice a day and more often if possible. The more constant you keep the FC at shock level the faster you can kill the algae. You keep the FC constant by testing and adding more chlorine to bring it back up to shock level. Run the pump 24/7 and brush the pool to break up any biofilms. You really can't overbrush but use a nylon brush on new plaster.
IF you do this you will get rid of the green very quickly. I have seen pools go from swamp to cloudy in 24 hours and then a few more days for the filter to clear the dead algae many times.

Without GOOD test results you have no idea of HOW MUCH and HOW OFTEN of WHICH chemicals you need. Pool store testing is well and good in some cases but you really can't go running there two or three times a day to get your water tested.

How much did your new pool cost? Now, is around $50-$80 a lot to spend on the one tool that will keep your pool in top shape and save you a lot of money in the long run, not just on chemicals but on protecting the plaster and getting the maximum life out of it? I think not. Get yourself a good test kit! Best bang for the buck is the Taylor K-2006 (not the K-2005).

Algae is very easy to kill but we really need to know current water parameters and NOT from strips. They are just too unreliable, particularly with CYA, CH, and pH.
To kill algae and keep it away we need to start with an accurate and precise CYA reading and need to know exactly which form of chlorine you are using if you are not using bleach or liquid chlorine because it can make a difference.

Hope this helps.

[waterbear]

Did all of that. Honestly, we have tried it all. Still there...a little worse. Is it possible that minerals or something is leaching from the gunite that can cause stains which are almost impossible to remove? The pool's gunite cured during heavy pollen season. The pool is under trees. If the plaster folks did not wash out all of the pollen properly..could this be causing a problem?

In a word, no.
Pollen floats on the surface and does not stain under the water. It can deplete chlorine and allow algae to grow. Your description of the problem and how it occurred and the things you have done to treat it leave no doubt in my mind that you are dealing with algae and just not doing what you need to do to get rid of it. First step is a good, current CYA reading.