I think it is algae now....

[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.

[waterbear]

You have, once again, missed the point entirely. Using monochloramne to kill algae is very different than killing algae with chlorine and it is also very different than using either chlorine or chloramines for sanitation of drinking water so the studies you cite are not meaningful to the discussion. You are comparing apples and oranges. These are exactly the same type of studies that are often quoted by the 'chlorine is bad for you, don't put it in your pool' camp. They really are meaningless when it comes to pool sanitation, however. There has been much discussion of this on this and other forums in the past so it is really an old topic. You might want to use the seach feature and see what has been said previousloy by Ben and others from before you became more active in the forum.

Monochloramine is a nitorgen containing compound and as such, it is consumed by the algae which is why it is effective at killing algae compared to chlorine. Patents have even been taken out based on this. Pool service techs used to use anhydrous ammonia added to a pool in conjunction with shocking to kill algae by this method. Today various orgainic ammonia products such as Yellow Out by Coral Seas are based on this technique. It is fast and effective at killing algae but the drawback is the fact that FC drops to 0 ppm while TC is high until all the chloramine is destroyed. However, this does happen rather quickly in an outdoor pool with repeated shocking so it is not a major issue as long as the pool is not overdosed with the ammonia source.

As far as pH effects on hypochlouous acid concentration in a stabilized pool, that is an entirely different subject that I was referring to. Once CYA enters the equation the effect of pH on HOCl and OCl- concentrations basically goes out the window. By keeping the pH high you favor the formation of monochloramine (as opposed to other chloramine species) which will help and not hinder the killing of algae.

Moderators, this thread hijack would probably be better if moved to the China shop since the matierial is not relevant to the OP's question but is a side tangent by smallpooldad.

[AnnaK]

My understanding of mustard algae is that it tends to creep up on the sides of the pool. Your stuff appears to settle in and get trapped by the small creases in the liner.

You said the pool hasn't been used or vacuumed in a week which is a good long time for dirt and dust to collect on the bottom.

I'm all for brushing to keep the material in solution with the pump running. Since you can't test for CCs you could try an alternate method: test FC after the sun is off the water and test again early in the morning. If the difference is zero then there's nothing in the water for the chlorine to act on.

AnnaK

[waterbear]

My understanding of mustard algae is that it tends to creep up on the sides of the pool. Your stuff appears to settle in and get trapped by the small creases in the liner.

You said the pool hasn't been used or vacuumed in a week which is a good long time for dirt and dust to collect on the bottom.



AnnaK

Anna, Good Catch!

Mustard will not just settle in the cracks but ususally covers the sides and bottom, particulalrly in the shady parts of the pool. If you brush it away it's usually back in a few hours. This is not what you have been describing.
Not vacuuming for a week will allow a lot of dirt to collect in the cracks. I suspect that is what is going on here.

[denanbob]

This is interesting because the chlorine does not seem to be budging at all (not losing any). I cannot get an accurate chlorine reading. I have the WalMart test and when I test chlorine, it is a dark dark orange color. So I tried last night to dilute it until it turned yellow and it never did. It went straight from orange to clear so I can't tell what the chlorine reading is. As of Monday when my chlorine was 2, I've added a total of 5 3qt. jugs of 6% bleach which would equal almost 4 gallons which SHOULD have raised my chlorine to a total of 26. However, even when I dilute up to 7 times (which if the color was equal at the 5 line would be 35 chlorine) it is still dark orange. So is my chlorine even higher than 35? Yikes I hope not. The stuff had returned yesterday although not as heavy and I brushed it to mix it back up with the chlorine. There was some yellow staining on the walls here and there, but mostly this stuff in my original picture pretty much concentrated to one area of the pool (NOT the part in the most shade). I haven't kept up with the discussions between smallpooldad and waterbear because it is beyond my level of comprehension (LOL), but just wanted to update everyone since you all were kind enough to help me with my problem (even though the verdict is still up in the air as to what the problem actually IS).

[waterbear]

It's not mustard. Mustard doesn't settle in the cracks. Also, when you brush or vacuum it it's back in place in about an hour or two. I suspect it's just normal junk from not vacuuming, possibly some pollen mixed in to give it color.
I would strongly suggest getting a better test kit that uses FAS-DPD chlorine testing such as a Taylor K-2006 or a TF100 from TF Test Kits. (google them, it's owned by someone who is a member here but I don't think he is active on this particular forum much but he is busy on another pool forum.)

[chem geek]

I've responded to smallpooldad's post above in this thread in The China Shop.

[smallpooldad]

Question posted here:

http://www.poolforum.com/pf2/showthr...6952#post56952