Does a green pool definitely mean algae?

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The "advice" on this thread is getting pretty far-fetched. I implore all the responders to first re-read the OP's comments about never having added anything to the pool except bleach.....that sorta' makes copper a non-issue.

Secondly, I have seen pools (mostly mine) with mustard algae, green algae and mixtures and ratios of all kinds of algae......they never look like the pictures the OP has provided us. A reasoned study of the info available also details to us a very, very low FC loss.......a pool with enough algae to discolor a pool will consume chlorine far, far faster than OP indicates is happening.

I cannot, yet, resolve the problem with this pool water. Back to the principles of BBB, we simplify everything we can and we test carefully to make the appropriate adjusments. This pool seems outside the normal parameters for which we test.......making it seem only logical that what's involved is a parameter for which we do not test. Just what that parameter is.....I don't know.
 
I agree with duraleigh. This is a strange one.

I just want to add that there was some FC loss overnight last night so it is important to keep the pool at shock level until there isn't any more FC loss overnight. That may not solve the "green problem" but it needs to be done in any case.
 
Duraleigh, what "advice" are you referring to?

1) Testing for copper? I don't think it is copper, but there is no harm in having it tested, is there? I just wanted to know if there was any. I was not recommending any treatment for copper. I don't see any reason not to test since it was raised as an issue by several people, including you.

2) Shocking to 18 ppm, as Richard noted was necessary to kill mustard algae, but hadn't been achieved yet?

3) Using "Yellow-Out"?

Perhaps you have never seen algae that looked like the pictures, but I have. Mustard algae grows much faster when it is stirred up; and the OP's auto vacuum is constantly stirring up the algae. Mustard algae is highly resistant to chlorine and won't consume it as nearly as fast as other types of algae will. What advice is "far fetched"? What is your recommendation?
 
An additional note:

Yellow-Out does not contain sodium bromide. A product called "Yellow Treat" does contain sodium bromide. In my opinion, either one will work to control mustard algae. Use of sodium bromide will convert the pool to bromine for a while, but as long as the chlorine/bromine level is checked and maintained daily or there is a constant supply of sanitizer, as from a chlorine feeder, the bromine will work just fine until it reconverts to chlorine. Unless anyone has a better idea, or a good reason not to proceed with a mustard algae treatment, I think it is important to get the treatment started as soon as possible.

I do acknowledge that this is not the usual presentation of mustard algae. However, I have seen similar outbreaks. In my opinion, all indications point to Mustard algae as the most likely cause.

Although I don't think that copper is causing the problem, I would still like to have it tested. I believe in testing everything possible, especially when there is a disagreement or "mystery" about the cause. I would also like to request a test for ammonia and phosphates. The more detailed information, the better.
 
I believe the Yellow Out you are referring to has an MSDS here for the product shown here. This appears to be EDTA which is normally used as a metal sequestrant (it's not as good as other metal sequestrants that use HEDP). The instructions for Yellow Out have you first raise the pH above 8.0 (which could result in some cloudiness or scaling, depending on other water parameters). You then add 2 pounds of Yellow Out per 15,000 gallons. You then add Cal-Hypo or liquid chlorine (chlorinating liquid or bleach) to add about 10 ppm FC. You then circulate for 24 hours. Finally, you add another 10 ppm FC of chlorine.

Their process is patented here where interestingly the patent is essentially using chlorine plus ammonia to form monochloramine which is the primary decolorizing agent. I am going to guess, on the basis of this patent, that EDTA breaks down under higher levels of chlorine in alkaline (higher pH) conditions. I am guessing that they are using EDTA rather than ammonium sulfate in their product since they don't have to label the ingredients and it makes things less obvious.

So basically this product just forms chloramine to kill the algae and then you add more chlorine to get rid of the chloramine.

Of course, you could just shock with chlorine alone instead, but would need higher levels of chlorine when there is higher CYA in the water. Using ammonia or bromine gets around the CYA issue by forming monochloramine or bromine that are not affected by CYA. It is not an approach normally promoted on this forum.

Richard
 
Just a newbie here, so take that into account...

But I've got to say this looks a lot like our pool did a couple of weeks ago. Actually, ours was darker, but after the addition of bleach it brightened up and on day2 was a pretty good match for those photos. Absent a sufficient test kit at the time, I added more bleach at regular intervals for several days and the green faded to milky then gradually resolved. When I finally got the test kit it tested at about 37 ppm FC -- way too high of course, but if there isn't any harm to briefly raising the OP's FC to a somewhat higher level than currently. that would seem to be a cheap experiment. Wouldn't checking the filter also be revealing? I imagine Algae would result in considerable amount of green gunk in the filter. At least it was for ours, but we did not check until after it was dead or dying (gray-green gunk).... I imagine a chemical green would just pass through the filter. In my simplistic view it's either animal, vegetable or mineral :). Bleach should take care of the first 2, with dead bodies in the filter.
 
Ok, here is an update. The pool is still green. This morning as a gazed out through the pouring rain it appeared to be a little blue-ish greenish. It was hard to tell because of the rain. It should stop raining and I will take an updated picture this afternoon. We kept the pool at green algae shock level (13) on Sunday and Monday. We took it up to Mustard algae shock level Monday night - 19. Tuesday morning the FC level was at 17 and Tuesday evening it was at 13. The water still looked the same. I do not have an automatic chlorinator. I pour the bleach in by hand. My husband and I were searching for any other variables that may have affected the pool. This is the only things we came up with - maybe the sand in the filter is the cause. We purchased the pool and all accessories from a couple who had it up in their yard for one summer. It sat in the in garage for one winter and one summer, we bought it and it sat in our garage for one winter. We had it put up this June, filled it and started swimming in the middle of June. I have no idea if the couple who owned it before us used baquacil or some other product. The water has been clear ever since the day we filled it. I don't know if it could take two and half months to start seeing effects from baquacil left in the sand. I wish that I hadn't stumped everyone. Photos coming later. Thanks for your help so far!
 
The color change is very good news. It is important to keep the chlorine at shock level until all of the green/yellow is gone or it will come back. The next challenge will be to remove the dead algae. A sand filter will have a hard time removing the dead algae because it is so fine that it can go right through a sand filter. If the water does not begin to clear on its own, you can use a clarifier to help or you can use a "floc" to drop the algae to the bottom and then vacuum to waste.

Mustard Algae is brought in by rain, so it is a good idea to either shock or use a maintenance dose of "Poly 60%" algaecide after any rain, especially after heavy rain. Usually shocking to about 10 ppm after a heavy rain will prevent further outbreaks. After shocking retest the chlorine level at night and again the next morning to look for excessive overnight chlorine level drops, which could indicate the need for further shocking. If the chlorine levels hold steady or have minimal loss then you are good.
 

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Have you backwashed the filter recently? If not it is probably a good idea to do so now. That will help the filter clear up the cloudy water more quickly.

It can take a sand filter up to a week to clear up the water once all the algae (if there ever was any) is dead. You should see a visible improvement in the water from day to day. If it doesn't make daily progress there might be something wrong with the filter or the algae might not all be dead.
 
I backwashed on Monday when it was still green. Should I backwash again? The pool looks pretty much like it did yesterday - nuclear blue. Should I continue shocking until I can start seeing the bottom? The pump has been running on high 24/7 for a week now.
 
After a whole lot of POP (pool owner patience) the pool is finally sparkling again. I decided not to add anything but bleach. Although the FC never seemed to drop like I would have expected with algae, I guess it must have been. It took two weeks of shocking though to get rid of the green and then nuclear blue. Now all the numbers are perfect and the water is the clearest I have ever seen. I'm still baffled, but pleased that the pool is clear again. Thanks so much for everyone's help. I think the most important thing I learned was patience.
 
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