Pool Chemistry HELP!!!

flbranham said:

Does not have sulfur. You can drink it and it does not taste bad.

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JoyfulNoise said:

So there’s definitely some kind of interference going on here. Water with a CC level above 2ppm would have a very distinct, harsh “chlorinated swimming pool” odor and anything above 5ppm would smell so bad that no one would want to swim in it or spend any length of time around the pool.

All I can think of is your well water has some kind of organic compound in it that is registering on the test. This happens a lot in hot tubs where organic CCs build up and are persistent - meaning that further elevation in FC, even beyond shock level, will not destroy them. One sees this in a “breakpoint chlorination” graph as a persistent level of CC that never goes down. Of course, in a hot tub, you simply dump the water when it has become fouled. A pool is a much harder problem.

I’ll have to think about this a bit more....

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JoyfulNoise said:

So there’s definitely some kind of interference going on here. Water with a CC level above 2ppm would have a very distinct, harsh “chlorinated swimming pool” odor and anything above 5ppm would smell so bad that no one would want to swim in it or spend any length of time around the pool.

All I can think of is your well water has some kind of organic compound in it that is registering on the test. This happens a lot in hot tubs where organic CCs build up and are persistent - meaning that further elevation in FC, even beyond shock level, will not destroy them. One sees this in a “breakpoint chlorination” graph as a persistent level of CC that never goes down. Of course, in a hot tub, you simply dump the water when it has become fouled. A pool is a much harder problem.

I’ll have to think about this a bit more....

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Flying Tivo said:

Try cleaning your test tubes with rubbing alcohol and see if it makes a difference.

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Flying Tivo said:

Try cleaning your test tubes with rubbing alcohol and see if it makes a difference.

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Mr Bruce said:

What does a FC/CC test of your tap water look like?

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JoyfulNoise said:

Not sure what kind of lab equipment you have available but if you could add 1 mL of 10% liquid chlorine to a liter of tap water and then take 1 part of that solution and add it to 9 parts tap water (1/10 th dilution) then you’d have a water sample with about 10ppm FC in it. You could then test that and see if your tap water registers high CC after chlorinating it. If it doesn’t show any CCs, then the problem is isolated to your pool water.

Those FC/CC numbers make no sense. If you truly had 14.5ppm CC, you’d smell it. The other thing you can do is call up Taylor Technology l’s customer tech support number and ask them for advice on what could possibly be causing this interference. Perhaps one of the reagents is compromised. If you did that tap water experiment above, you could at least isolate the problem to your pool water or fill water.

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JoyfulNoise said:

Not sure what kind of lab equipment you have available but if you could add 1 mL of 10% liquid chlorine to a liter of tap water and then take 1 part of that solution and add it to 9 parts tap water (1/10 th dilution) then you’d have a water sample with about 10ppm FC in it. You could then test that and see if your tap water registers high CC after chlorinating it. If it doesn’t show any CCs, then the problem is isolated to your pool water.

Those FC/CC numbers make no sense. If you truly had 14.5ppm CC, you’d smell it. The other thing you can do is call up Taylor Technology l’s customer tech support number and ask them for advice on what could possibly be causing this interference. Perhaps one of the reagents is compromised. If you did that tap water experiment above, you could at least isolate the problem to your pool water or fill water.

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JoyfulNoise said:

Did they elaborate on their findings at all? Was this a pool company that tested the water or something else? What filtration system for the well did you get?

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JoyfulNoise said:

Ok, then this might explain things a bit. I believe high manganese levels will interfere with the DPD test but you should confirm that with Taylor Technologies.

There are two forms (oxidation states) of iron - Fe(2+) and Fe(3+). Iron in the +2 oxidation state is called ferrous iron and is very soluble in water. Iron in the +3 oxidation state is called ferric iron and it can be soluble in well water but only if dissolved oxygen is not present otherwise it forms an insoluble oxide (rust). So what iron filters attempt to do is to inject either air or chlorine or potassium permanganate into the water to oxidize any Fe2+ to Fe3+ and then have the Fe3+ react with injected air to form insoluble rust particles that will get trapped by the filter. Some filters use a specialized sand, called green sand, which help as a catalyst to make the process go faster. Manganese can also be dropped out of solution BUT if the levels are too high, it’s impossible to get all the manganese out.

You need to be really careful with your fill water. Iron stains on a pool surface are treatable but manganese stains (black colored stains) are not easily removed. You need to use as little fill water as possible and let rain water help you as much as possible - you might even consider buying or building a rain harvesting system to collect rain water. You well water, even when treated, is going to be an ongoing source of problems for your pool if the household filter can’t get rid of all the iron and manganese.

One more question - do you know if your well tested positive for iron bacteria? Iron bacteria can sometimes occur in high iron wells and, without proper chlorination, coins get into your pool and cause problems as well. It usually tested for in a well so I would think you’d have been informed. If not, ask your testing company.

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