Numbers = confusion

Ok guys I usually hide in the background and observed, but not this time. I have the Taylor k-2006 testing kit. When I opened my pool I my added Clorox, as informed last year ( 4 gallons day 1, 4 gallons day 2, and 2 gallons each for day 3 and 4. Pool cleared ( somewhat) and vacuumed to wasted. I've been socking the Clorox to it in effort to clear it up. Over that last 2 weeks I've probably dumped 15 gallons of Clorox in it. Free chlorine is 1 ppm combined chlorine is 64ppm( I believe this is wrong), ph 7.2, alk is 50, CH is 20 and CA is 30. It's a above ground pool 24 x 52 with sand filter. I might have screwed up the chlorine test. i know CH and alky need raising. Any other advice to clear this cloudy mess up? Thanks!

You need to follow a more rigorous process and you need to get your test numbers exact. Once your FC goes over 10ppm, you can NOT do any other tests as the high chlorine levels chemically change the indicator dyes (pH, TA and CH) and the CYA test cannot be performed at high FC or when the pH is out of range (too acidic or too alkaline).

So, first things first, you need to post test results. Start with FC and CC. If the FC is below 10ppm, then you can do all the other tests.

Next, you need to shock chlorinate your pool. Here's the process roughly laid out -

1. Drop the pH to 7.2. If it's at 7.2 or lower, then move on to step 2.
2. Calculate your shock level FC for your CYA level using the Ben's Best Guess Chart.
3. Turn on all pumps and water features and leave them running
4. Add enough bleach to raise your pool water to Shock FC levels. This step could take several iterations of testing the FC level and adding bleach to get to Shock level. Add bleach, let the pool water circulate for a minimum of 30mins, then test FC. Use the 10mL sample size for FC testing to conserve DPD powder and reagent drops. KEEP A LOG OF ALL FC AND CC DATA.
5. Maintain Shock FC levels by testing and adding bleach at least every 2 hours initially. In the beginning you are likely to see your FC fall very fast, this is normal and it is the reason why you need to stay on top of it in the beginning. Also, BRUSH YOUR POOL A LOT!
6. Each evening, after the sun sets or there is no direct sunlight on the pool, re-adjust the FC to shock level and make sure you accurately record the FC and CC values. Then go to bed.
7. Early the next morning, test your pool immediately before sunrise or any direct sunlight on the pool. Calculate the overnight chlorine loss (OCL) by subtracting the FC numbers from the previous evening.
8. If your OCL is less than 1ppm AND your CC's are less than 0.5ppm AND your water is clear, then dose the water with bleach back up to shock FC and hold it there for one more day. Afterwards, let the FC drift down to normal. IF you did not pass those three criterion, then you need to keep shocking the pool water and repeat the process until you do.

During this process, keep an eye on your sand filter pressure as the dead algae buildup might require you to backwash the sand filter periodically during the shock process. A good rule of thumb for when to backwash is when the filter pressure rises by more then 20% of the clean pressure. So if your clean pressure in 20psi, then you backwash when the filter hits 24psi.

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Originally Posted by SunnyOptimism

You need to follow a more rigorous process and you need to get your test numbers exact. Once your FC goes over 10ppm, you can NOT do any other tests as the high chlorine levels chemically change the indicator dyes (pH, TA and CH) and the CYA test cannot be performed at high FC or when the pH is out of range (too acidic or too alkaline).

So, first things first, you need to post test results. Start with FC and CC. If the FC is below 10ppm, then you can do all the other tests.

Next, you need to shock chlorinate your pool. Here's the process roughly laid out -

1. Drop the pH to 7.2. If it's at 7.2 or lower, then move on to step 2.
2. Calculate your shock level FC for your CYA level using the Ben's Best Guess Chart.
3. Turn on all pumps and water features and leave them running
4. Add enough bleach to raise your pool water to Shock FC levels. This step could take several iterations of testing the FC level and adding bleach to get to Shock level. Add bleach, let the pool water circulate for a minimum of 30mins, then test FC. Use the 10mL sample size for FC testing to conserve DPD powder and reagent drops. KEEP A LOG OF ALL FC AND CC DATA.
5. Maintain Shock FC levels by testing and adding bleach at least every 2 hours initially. In the beginning you are likely to see your FC fall very fast, this is normal and it is the reason why you need to stay on top of it in the beginning. Also, BRUSH YOUR POOL A LOT!
6. Each evening, after the sun sets or there is no direct sunlight on the pool, re-adjust the FC to shock level and make sure you accurately record the FC and CC values. Then go to bed.
7. Early the next morning, test your pool immediately before sunrise or any direct sunlight on the pool. Calculate the overnight chlorine loss (OCL) by subtracting the FC numbers from the previous evening.
8. If your OCL is less than 1ppm AND your CC's are less than 0.5ppm AND your water is clear, then dose the water with bleach back up to shock FC and hold it there for one more day. Afterwards, let the FC drift down to normal. IF you did not pass those three criterion, then you need to keep shocking the pool water and repeat the process until you do.

During this process, keep an eye on your sand filter pressure as the dead algae buildup might require you to backwash the sand filter periodically during the shock process. A good rule of thumb for when to backwash is when the filter pressure rises by more then 20% of the clean pressure. So if your clean pressure in 20psi, then you backwash when the filter hits 24psi.

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My apologies for the side track, but I don't remember reading before that CYA cannot be checked at high CL levels. How does CL affect the CYA test? What's considered "high"?

Thanks. :)

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Originally Posted by JimK

My apologies for the side track, but I don't remember reading before that CYA cannot be checked at high CL levels. How does CL affect the CYA test? What's considered "high"?

Thanks. :)

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Hey JimK. Yeah, sorry I should have qualified that as a personal preference. The Tatlor website lists no official interferences for that test but I tried the CYA test several times at 30ppm FC and got a value that was 30ppm lower than at Target FC levels. My pH at that time was above 8.0 as well so I just decided that it was a bad idea to attempt those tests during any kind of shock procedure.

I am open to persuasion that it was operator error, but I repeated the test about 5 times and I got the same results. I appreciate a possible chemical explanation but I never got one.

Fc was 1ppm, the cc is what I wasn't sure about being correct. I've keep my shock level at 25 for 2 days. ( as close as I could). I had to go out of town. I've brush, brushed and brushed.. Then I brushed some more lol! Ph stays around 7.2-7.6. I'm on the way to the store for more Clorox.

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Originally Posted by Olugly

Fc was 1ppm, the cc is what I wasn't sure about being correct. I've keep my shock level at 25 for 2 days. ( as close as I could). I had to go out of town. I've brush, brushed and brushed.. Then I brushed some more lol! Ph stays around 7.2-7.6. I'm on the way to the store for more Clorox.

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Great. Keep up the shock level. But you need to get the FC and CC measurements corrected you won't know if you've reached the end unless you can measure FC and CC.

Can you explain what you're doing for those tests and describe what you're seeing.

Sunny,
You really need to check your information before giving out advice.

I've never heard that if FC is 10 or higher that CYA cannot be measured. I don't know where you got that from and I would never advise it.

Further, what high FC DOES do is cause pH readings to appear high--that's why you need to use the R-0014 for the pH test, not the R-0004 when the FC is 10 or higher. If your FC is, say, 30 and your pH is 8, then trying to drop your pH to 7.2 will actually drop it far lower PUTTING YOUR LINER AT RISK!

You can also add a couple of drops of chlorine neutralizer before you test.

Then you give advice to raise FC to the shock level. How do you know what the shock level is if you can't measure CYA with FC at 10?

Further, one does NOT need to add chlorine every 2 hours when fighting a bloom. Testing and adding chlorine 3x/day is enough.

Brushing "a lot"? Brushing and vacuuming (to waste, not to the filter) once a day should be sufficient--and it's plenty of work as it is!

While an algae bloom is a pain the lower extremities, it is still possible to clear it up easily without working oneself to a frenzy. If you work, you cannot be checking and adjusting FC levels every 2 hours. The whole idea of our systems is to keep things as simple as possible.

We have more than one stickied thread on how to clear an algae bloom. It's not hard and you don't have to drive yourself crazy. You DO have to be consistent and persistent.

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Originally Posted by CarlD

Sunny,
You really need to check your information before giving out advice.

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Now, now, just trying to be a nice and helpful member of the community here...but if you want me to be more specific with fact-checking, how's this -

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I've never heard that if FC is 10 or higher that CYA cannot be measured. I don't know where you got that from and I would never advise it.

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Based on my experience with testing CYA at high FC. Got false low readings. Already explained that in a previous reply. Since that was a personal opinion, I'm totally willing to retract it. Just because I had some off measurements at high FC doesn't mean others will.

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Further, what high FC DOES do is cause pH readings to appear high--that's why you need to use the R-0014 for the pH test, not the R-0004 when the FC is 10 or higher. If your FC is, say, 30 and your pH is 8, then trying to drop your pH to 7.2 will actually drop it far lower PUTTING YOUR LINER AT RISK!

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Couple of things to refute here.

First, both the R-0014 and R-0004 are the same chemistry - Phenol Red (links to MSDS's are HERE and HERE). The only technical difference between the two is that they have different phenol red concentrations and they use slightly different color comparator blocks. The R-0004 is what is shipped and used in all K-2006 test kits.

When FC is above 10ppm but below 25ppm, Phenol Red starts to convert into Chlorphenol Red. The Chlorphenol red is an indicator for lower pH (somewhere down at 3 or 4, I believe) so a fraction of the chlorphenol red turns purple colored and causes a false high reading. Above 25ppm, the conversion of phenol red to chlorphenol red is almost fully completed and thus makes the pH indicator useless.

Second, I never stated that the OP should adjust his pH based on false values. I was specifically cautioning against that.

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You can also add a couple of drops of chlorine neutralizer before you test.

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You SHOULD NOT use the sodium thiosulfate chlorine reducer to take down the FC level prior to pH testing. There is a good discussion of that HERE with pictures in this thread showing how the thiosulfate changes the color of the pH indicator for the same water samples. The thiosulfate Cl reducer is both alkaline in nature and it's reactions with Cl raise the pH of the solution by an unknown amount thus making the subsequent phenol red test result invalid.

The only way to test for pH with an FC between 10ppm and 20ppm is to dilute the pool water sample with DISTILLED water as the distilled water has a pH of 7.0 and no alkalinity. Therefore the pool water's alkalinity can buffer any pH change from the distilled water addition while allowing the dilution to reduce the FC level.

A rigorous technical discussion of ways of reducing the effects of chlorine on phenol red pH indicators can be found HERE

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Then you give advice to raise FC to the shock level. How do you know what the shock level is if you can't measure CYA with FC at 10?

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Nice rhetorical trick but you're twisting my words. The OP stated that his CYA was 30 (or maybe it was 40), so you go based on that number and do an accurate measurement of CYA later.

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Further, one does NOT need to add chlorine every 2 hours when fighting a bloom. Testing and adding chlorine 3x/day is enough.

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We all fight our algae blooms differently. If you have the time to do it every two hours, then keeping the chlorine level at or above shock level helps enormously because it doesn't allow the algae to get a foot hold. Algae double their population sizes roughly every 3-8 hours (see posting HERE), so you need to keep your FC at or above shock levels in order for the kill rate to be greater than the growth rate. HERE IS A LINK on the various kill rates of chlorine for different pathogens. The column labelled "CT factor" (chlorine concentration multiplied by kill-time) lets you compare the relative effectiveness of chlorine on different pathogens (low CT factors are good).

Being experienced, you know as well as I do that the concentration of FC in your water volume is variable from top to bottom and from well-mixed to stagnant spots. Algae concentrations and colony sizes also vary from place to place in a pool. As well, chlorine kill times are typically measured in controlled Petri dishes where the pathogens are not free-floating in a giant volume of water (meaning the effectiveness of chlorine in you pool is not the same as chlorine in a Petri dish). So the best bet is to maintain your FC above shock levels as best you can. If you happen to have a day-job, then you just do your best and maybe seek the assistance of a friend, family member or neighbor's kid to help you out.

I would advise that these types of treatments be started on the weekends (starting on a Friday) as it allows the pool owner to concentrate on the task at hand and really get a good go at it. A little bit of planning and proper chemical preparation can really make the process quite easy to pull off.

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Brushing "a lot"? Brushing and vacuuming (to waste, not to the filter) once a day should be sufficient--and it's plenty of work as it is!

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See above, to each his own. Brushing helps mix the water column (especially if you have one of those Whale-Tail brushes) for better chlorine distribution and also mixes up the dead algae in the pool so the filter can work on it. If you can vacuum to waste, that's great but not always feasible - depends on your equipment setup and if water replacement is expensive in the region you live in.

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While an algae bloom is a pain the lower extremities, it is still possible to clear it up easily without working oneself to a frenzy. If you work, you cannot be checking and adjusting FC levels every 2 hours. The whole idea of our systems is to keep things as simple as possible.

We have more than one stickied thread on how to clear an algae bloom. It's not hard and you don't have to drive yourself crazy. You DO have to be consistent and persistent.

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Never been frenzied or crazy in my life...

How you choose to treat your pool is your choice and your selection.

But advising people to do far more work than we have found necessary defeats the purpose of Pool Forum, which is helping make it EASY as well as effective to care for pools.

Over the many years of this forum (I'm here 14 years) and the thousands of people we've helped clear up algae blooms, we HAVE found effective means that allow people to solve their problem without having to hover over their pool every 2 hours. Think about is: It's kind of hard to maintain a pool if you can't work at your job because you're checking it every 2 hours. That's fine for work-at-homes and retirees, but not people who have to go to work every day to make a living.

We have a number of permanent pertinent threads on this forum that clearly explain, in simple language, time-tested ways to clear a pool of algae without going insane. I won't repeat them again.

Yes, you are entitled to maintain your pool any way you like. You are even entitle to explain how you do it. You can even advocate (some) alternate forms of treatment.

But you are NOT entitled to discard and dismiss the time-tested and proven methods advocated here and advise people NOT to follow them.

Now I am going to move this thread to the China Shop, which is the place where you are allowed to challenge our methods.

I tested and compared ph readings (7.4). As in the past, I have raised the pool back to shock level once more. Maybe I'm missing something simple.. Thinking to hard as they say. I've maintained shock levels before for over 48 hours. Over the last 2 weeks this will be 21 gallons of bleach. I only had time to do a quick test this morning.. Ph is 7.2 at 30- shock level, added 3 more gallons of Clorox. I will retest after work

Is the 30 the CYA level or the FC level? If it's the FC level, your pH may well be far lower than 7.2. If it's 7.2 when the FC is below 10ppm then it's OK. Chlorine is more effective when pH is 7.2 than 7.6. But if it's 7.2 when FC is 30, you should add Borax until you get a reading between 7.6 and 7.8, just to be safe.

Normally, what we recommend, is keep your pool at shock level continuously until you don't get a precipitous drop in FC between dusk and dawn. But shock level is determined by CYA level. However, the highest shock level we usually recommend is an FC of 25 when CYA is over 100. However, the only risk of keeping FC at 30 is you MAY bleach your liner. If it's an old liner, my feeling is Who Cares? If it's a newer one, you may want to be careful.

You will need to be persistent. It's not how much chlorine bleach you add--it's how well you can maintain the shock level. We normally recommend checking it 3x/day. Morning, noon and night. If you cannot manage the noon test, then morning, just after work, before bedtime instead. You also should vacuum to waste 1x/day and brush the pool's sides and bottom 1x/day to knock algae loose and get it and dead algae out of the pool.

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Originally Posted by SunnyOptimism

The Tatlor website lists no official interferences for that test but I tried the CYA test several times at 30ppm FC and got a value that was 30ppm lower than at Target FC levels.

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It is possible that at high FC levels that these chlorinated isocyanurates do not precipitate with melamine in the CYA measurement test because the chlorine is where the hydrogen would be in CYA so no hydrogen bonding occurs. The CYA level could measure lower by as much as the FC level.

This is easily overcome by dechlorinating the water sample such as by using the Taylor R-0007 thiosulfate reagent or other reducing agent such as hydrogen peroxide. One would add this to the water sample before adding the melamine.

Thanks for the clarification and useful "hack", Richard!