I think it is algae now....

[smallpooldad]

It might be better to bring your pH down to 7.4 as chlorine tends to work better at a lower ph, some say 7.2 but I am not sure if that is ok for a vinyl pool, so I indicated a pH of 7.4. To go from 7.8 to 7.4 you would need to add an additional 17.5 oz of Muriatic acid and also add 15 oz of baking soda to hold your alkalinity at 120, over and above the figures listed below, per every 10,000 gallons.

If you are adding liquid chlorine via 5.25% bleach to get to 15 ppm, you might wish to add approximately 7.53% Muriatic Acid, by volume of the amount of liquid chlorine. This is done to hold the pH at the starting point, assuming you are using 5.25% liquid un-scented bleach; otherwise the pH will rise and the chlorine will be less effective.

If using 6% liquid bleach you will need to add 8.73%, 8% Ultra Bleach (liquid) would need 11.78%.

So if you add 100 oz of 5.25% liquid chlorine you would add 7.5 oz acid, do this every time you add chlorine. Once the chlorine goes over 10 ppm it is harder or impossible to get an accurate pH reading. This would negate this problem. Non-liquid bleach numbers are different.

If you know how to use an Excel spreadsheet, and are technically inclined, the PoolSolutions spreadsheet is excellent for calculating your needs. It can be found here:

http://richardfalk.home.comcast.net/...lEquations.zip

As far as the future goes, once this algae is removed and based on a CyA of 50, you may wish to lower your pH to 7.5 (same as the eye) and and keep your FC at 6 (would kill most algae), you may get away with as low as FC 1.5. Holding a FC of 8 would nearly guarantee no return of mustard algae, see which works for you. At pH of 7.8 you need a little more chlorine (no biggy), minimum FC 2, FC 9 on the max side should assure no return of mustard algae. To kill most algae you would need FC 7.

Please note the above numbers are technically calculated numbers, and could vary from pool to pool eg. one pool may need, FC 7 to kill most algae, another only 5, and another 8. It all depends on your situation, wind, dust load, bugs, debris, leaves, etc.

The FC level needed may even vary at different times of the year depending on your location, the amount of shade your pool receives, and on your mean UV index, see here:

http://www.cpc.ncep.noaa.gov/product..._meanmax.shtml

It seems based on your problem that FC 2, is not a place to be so I would not go that far down at a pH of 7.8, or to 1.5 at 7.5 pH. At least not in July or August as the UV indexes are at their height as are temperatures, normally.

You maybe lucky that using the minimum number controls your problem, if it were me I would start at a FC 6 or 7, depending on where you want your pH to be, and lower the FC to the point where algae is not an issue, possibly no lower than FC 3, which is what the "Best Guess CyA Table" shows. If you raised your CyA you might need to raise the chlorine level, if you lowered the CyA to say 35 you might be able to lower them a little. Please note CyA can only be lowered by draining off water, something you may not wish to do. You will just have to try by trial and error which works best for you. Again it is best to refer to the "Best Guess CyA Table", here:

http://www.poolforum.com/pf2/showthread.php?t=365

An easy way to calculate how much chemical to use is here:


http://www.poolcalculator.com/


Hope this helps.

Aloha

[aylad]

You might want to consider lowering your pH to 7.2, as smallpooldad suggests, prior to shocking the pool, but there is no need to continually add acid as you add chlorine--you may get a very small and very temporary pH rise from adding bleach, but it's nothing permanent. The important thing is to get the chlorine up and keep it up, not letting it yo-yo up and down any more than possible.

I also would leave your TA alone....if it lowers (and it won't by much), then you'll be that much better off. TA of 120 is fine, but lower is even better. Concentrate on the chlorine and algae for now.

Janet

[denanbob]

Thanks everyone! I hope I didn't mess up and add way too much bleach. I added only 2 more jugs yesterday (6 qts.) but when I tested, the water was so dark orange that I couldn't get a good reading. (I only have the WalMart test kit). I diluted 5 times and it was still a light orange color (not yellow at all) and that would be at a 25 TC. I didn't even test any higher mainly because I didn't want to know. haha. I will wait for the bleach to come down to 15-20ish and try to hold it there. The 3 jugs I put in Monday should have only raised it to 15 based on the bleach calc program, but apparently somehow it shot way higher than that (unless the test kit just doesn't work at a certain level of chlorine???). I did not lower the PH before adding the bleach (read this too late), but I have some muriatic acid so I will put some in tonight.

Thanks again for all of the help everyone!

[aylad]

I wouldn't worry about the muriatic acid at this point--the high chlorine levels will give you falsely high pH readings, so you'll have no way to know when you've lowered it too much. Having it higher won't hurt anything, but getting it too low will ruin your liner. Leave the pH alone, and keep the chlorine around 20. You'll have to go a good bit above that to do any damage to your pool, so even if it is way high right now, any damage that was done would already be showing itself.

Janet

[smallpooldad]

Aylad, is correct the pH adjustment for each 100 oz of 5.25% Chlorine in a 10,000 gal pool is only about 0.15 pH to the up side , assuming a rise from FC 2 to FC 15, using 5.25% liquid chlorine, the pH would rise from 7.8 to about 8.3 pH.

As chlorine does work better at a lower pH it might be better to lower it some. For the sake of safety as it seems you are a little unsure of the accuracy of your test kit and starting this late you may want to use half the amounts recommended in my previous post. This should give a generous safety margin.

For the sake of interest chlorine concentration at a pH of 7.5 is approximately 50%, at a pH of 8.3 it is in the area of 15%, so you would need a lot more chlorine to do the job. See here:

http://edis.ifas.ufl.edu/EDISImagePa...RE%201&credits=

In fact generally speaking it is always a good rule when maintaining the pool, to use half the amount of muriatic acid mentioned and then re-check 4 hours later. In this case unfortunately one cannot check as the pH cannot be measured.

I do not know how accurate the Wal-Mart kit is, but the Taylor kit is considered by many to be accurate, so you might want to consider buying it.

[waterbear]

Actually, higher pH is beneficial when trying to kill algae because it favors the production of monochloramine, which is very effective at killing algae.
This is how the Yellow Out stuff mentioned above works!.
Also, the effects of pH on chlorine's effectiveness are minimal once there is CYA in the water. If you had no CYA then the pH does become imporatant but with a stabilzied pool there is very little difference in the activity of the chlorine with low or high pH. (Note to Smallpooldad, check with Richard (Chemgeek) on this if you don't believe me! He will tell you exactly the same thing! The chart that you gave the link to above is only valid for an UNSTABILIZED pool.)

[smallpooldad]

Waterbear,

I believe you, but (yes the eternal but), is it not true that one needs a greater contact time with monochloramines (in some cases as long as three weeks) to achieve the same result as lower ph and greater chlorine or in other words it could be a case of "half a dozen of one and half a dozen of the other". Maybe lower pH and higher chlorine as far as a pool goes might be better.

Although it is good for the treatment of Legionella Colonization but this is primarily due to the fact that chlorine treatments break down at higher temperatures of 25 to 42 C. found in buildings.

The American Society for Microbiology (ASM) found, with the Army Corp of Engineers, that the researchers (the largest single life science society, composed of over 42,000 scientists) that not only is monochloramine less reactive than free chlorine against a number of chemical threats, it also is a slightly less efficient disinfectant, requiring a longer time to kill bacterial contaminants, albeit with non-CyA water.

If the time difference is minimal then letting it float past a pH of 8.3, I agree, is certainly easier. My only concern would be that as the chlorine levels drop the pH would be too high for proper protection, or maybe some balance of non-reactive CyA is being achieved.

You are correct that the chart is for non-CyA water, but would it not be proportionate based on the CyA level, in otherwords a CyA of 30 at a pH of 7.2 would have more reserve of chlorine than at 8.3, and less at at a CyA of 50? Agreed this would be a smaller percentage than a CyA at zero.

I do think you make a good and valid point but I would be interested to know what you and others might think of these points and the following.

Here are some other thoughts from Lenntech a large water purification company in Europe that I believe use monochloramine.

Fortunately they do speak of the pluses and "drawbacks" of this system, the drawbacks concern me as regards to its use in a pool as written, because of what remains in the water after the treatment:

What are the drawbacks

Are organic chloramines formed?
When large amounts of organic matter are present in the water, organic nitrogen causes the formation of organic chloramines. These do not possess the same disinfection properties as inorganic chloramines. This situation occurs when organic matter contents exceed the 3 ppm boundary.

What is the reaction rate of chloramines?
The drawback of chloramines is that they are less reactive than chlorine. Part of the disinfectant remains in the water, where it will be consumed by bacteria or broken down. This process can take weeks. Contrary to chlorine, chloramines do not perish when the water lies still for a few days. As a result chloramines need to be removed from water. Chloramines can be removed by using granular active carbon or acetic acid.

What is the effectivity of chloramines?
In Massachusetts, research has been carried out to bring to light the death causes of people that used water disinfected by chlorine or chloramines. The results show that the number of people dying from bladder cancer was higher when the water was chlorinated. When water was disinfected by chloramines, people were more likely to die from pneumonia or flues. This may show that chloramines are less effective than chlorine for the elimination of pathogenic microorganisms.

Do chloramines form nitrates?
High amounts of ammonia serve as nutrients for nitrifying bacteria in the water, which can cause nitrate levels in the water to rise. Nitrate is converted to nitrite in the stomach. Nitrites can react to N-nitrosamines with proteins in fish. These compounds may be carcinogenic. Young children are more susceptive to nitrites. When children are below 0,5 years old they cannot drink nitrate-rich water, because nitrites cause the oxygen level in the blood to fall (Blue Baby Syndrome). It is advised to feed baby’s with water that has a nitrate content of below 25 μg/L.

Can ammonia cause corrosion?
When chloramines are chemically removed, ammonia may be released. The toxic effect that ammonia has on fish can be prevented by the application of biological filters, natural zeolites and pH-control.
Ammonia causes corrosion of lead and copper. Nowadays most waterworks are made of lead or copper. In Washington DC (US), increased lead concentrations in drinking water caused by chloramine disinfection caused a fuss in 2003. However, drinking water companies do not plan to switch back to using chlorine, because this can no longer comply with the standard for disinfection byproducts, which was lowered to 80 μg/L by the EPA. Chloramines are used because of a lower concentration of disinfection byproducts. To prevent corrosion, orthophosphates are added.

See here:

http://www.lenntech.com/water-disinfection/disinfectants-chloramines.htm

This statement worried me in particular:

"Kidney dialysis patients and people that own fish, reptiles or amphibians should be careful. With kidney dialysis patients the blood comes in contact with water in a semi permeable membrane. This can cause chloramines to directly enter the blood vessels. Chloramines are toxic to the blood."

In addition having Nitrates left in the water would that not make the pool susceptible to additional algae breakouts?

Should we worry?

You thoughts are welcome. Right now not knowing enough on the subject I sit on the fence, and for the meanwhile will take the more conservative approach of low pH and high chlorine for killing algae. But I could be swayed, this is interesting stuff. You know how I love science experiments, even though I am not a scientist.

Finally you, I, and hopefully others, might be destined for the China Shop on this one; this is, of course, the moderator's decision. Although I do not think I could add much, but others smarter than I in this area might be able to shed light on the subject. It is great that you brought this up, but it could end up being be a case of "the cure being worse than the disease," however my mind lies open.