pool consuming 6 ppm/day free chlorine

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twd000

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Feb 19, 2013
137
Tucson, AZ
this is my first summer owning a pool, followed BBB from the outset

water looks sparkly clear and feels good (a little irritating on the eyes). There is a bit on fine dust on the bottom, can't tell if it is desert dust or dead algae

walls are clean, I brush them once a week

The cost of chlorine is killing me; dumping in a gallon of 12% bleach every single day
I'm buying 8 gallons of 12% from E-Konomy pool every couple weeks
I also have two trichlor pucks in a floater trying to keep up

Last night at 9 PM, I dumped in another gallon of 12%, ran the pump for half hour, then tested- 8 ppm
This morning, 6 AM, tested at 6.5 ppm, zero Combined Chlorine
Tonight at 6 PM, tested at 2.5 ppm, zero Combined Chlorine

tell me this isn't normal; I can't be dumping $8 worth of bleach into this thing every day, all summer long :(

FC - trying to maintain 6 ppm
CC - 0
pH - 7.6
alkalinity - 100
CH - 240
CYA - 60
temp - 85 F
 
One gallon of 12.5% chlorinating liquid in 25,000 gallons is 6 ppm FC so since you say that is per day then that is indeed way too much. Your loss overnight of 1.5 ppm indicates that you've got something consuming chlorine in your pool and since that was over 9 hours, that loss rate over 24 hours would be 4 ppm just by itself. The additional loss of 2 ppm would be reasonable as loss from sunlight during the day. In other words, you should be at 2-3 ppm FC per day loss and the excess is something in your pool.

Is there any reason why with this overnight chlorine loss you didn't shock your pool to kill off whatever it is? Do you remember when this started happening (this high loss rate)?
 
twd000 said:
Last night at 9 PM, I dumped in another gallon of 12%, ran the pump for half hour, then tested- 8 ppm
This morning, 6 AM, tested at 6.5 ppm, zero Combined Chlorine
Tonight at 6 PM, tested at 2.5 ppm, zero Combined Chlorine
Click to expand...
Richard, he did the OCLT already as indicated above -- from 8 ppm FC at 9 PM to 6.5 ppm FC at 6 AM so a loss of 1.5 ppm which is too high. We want to see <= 1 ppm FC and really that's at shock levels so at normal levels it's usually a lot less than that, usually < 0.5 ppm if there is no sun at all.
 
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it didn't really start happening at any specific time. As the temperature has gotten hotter, days have gotten longer, chlorine consumption has gone up and stayed up

I thought 0 CC indicated no organics in the water?

so 2-3 ppm/day is the expect total daily loss rate for my pool in AZ?
 
Having no CC doesn't mean there isn't nascent algae growth. Until the quantity of algae is large enough and unless it disperses enough to get some chemicals into where you test for it, CC may not show up. Perhaps the FC dropped to low at some point and some algae started to grow consuming more chlorine and after that you've just been swinging but not high enough to kill it off. At least you can try shocking to see if that gets rid of the overnight loss and then lower the FC but always keep a minimum of never letting it get below 5 ppm. If you get to some normal chlorine loss, then you'll swing from 8 to 5 to 8 each day if you chlorinate every day, and that's the minimum you'd want to do.

There's also the possibility that you've got something growing in your sand filter, perhaps biofilm with channeling, but that's not likely. If it's easy for you to inspect the filter, then you can take a look. Also be sure to check the obvious places like skimmer baskets and filter baskets to make sure they are clean.
 
I've never shocked but I'm willing to try it to get the chlorine consumption down

By the table, I need to maintain 24 ppm, which is 4 gallons of 12.5% ? WOW!! Is it safe to swim at that level?

Should I use the overnight loss test to determine when I'm finished shocking, since CC is already zero?

As far as growth in my sand filter, that quite possible. I will backwash prior to starting the shock process.
I run my pump twice a day for 4 hours, this means there are two 8-hour periods every day when the water is sitting stagnant inside the filter. Should I run the pump more frequently to prevent anything from growing in there?
 
You can't swim during the shock process, and it can take awhile to get your chlorine loss under control. The more diligent you are about keeping the chlorine level up, the faster the process will go.

You will need to do the overnight loss test to be sure that you have finished the shock process. If you are losing chlorine at night when there is no sun, you have something consuming it.

During the shock process you need to run the filter 24/7. It isn't possible for algae to grow in the filter medium... algae requires sunlight for growth.

After you have met all of the criteria for completing the process, you can swim as soon as the levels come down a little from the shock level.
 
The growth in the filter I was referring to would be bacterial biofilms, not algae, but again, it's unlikely. It's more commonly found in commercial/public pools that have higher bather loads so have more delicious organics that get caught in their sand filters and where some such pools are not properly maintained so let the FC/CYA ratio get too low. I'd focus on the shocking and see if that fixes the OCLT in which case you won't need to worry about the filter being a source of the problem.
 
ok, another question

how do I set my Intellifo VS to run around-the-clock? I would like to avoid changing the set run schedule

but when I manually start Speed#2 (1500 RPM filter speed) it stops after the next "Running Schedule" sequence comes around
 

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twd000 said:
also I assume I will not be able to accurately test FC levels of 20-30 ppm, so do I just guess at the initial dose, then check once it comes down to normal levels?
Click to expand...

You would be able to if you have one of the Recommended Test Kits with the FAS-DPD test. If you wait for the FC level to drop down to 5 or 10ppm ... then you are losing ground.

EDIT: I just saw you do have the K-2006 ... that will test up to 50ppm no problems.
 
I have some very rough/flaked plaster and there are a few stubborn algae patches that reside in the pitted areas. Vigorous brushing does not remove them. Once I get up to shock level, can I take a pumice stone of something more abrasive to scrape them off?

is there any way to determine whether this is mustard algae, and go straight to MA shock levels? The rest of the water is clear so I'm not starting the process with a green algae swamp.

About how many days should I plan to keep the family out of the pool?
 
That is not the way dealing with mustard algae works (read the article in Pool School). What you described does not sound like mustard algae.

The shock process takes as long as it takes. The better job you do at maintaining shock level consistently and brushing, the faster you will pass the 3 criteria to stop.
 
twd000 said:
ok, another question

how do I set my Intellifo VS to run around-the-clock? I would like to avoid changing the set run schedule

but when I manually start Speed#2 (1500 RPM filter speed) it stops after the next "Running Schedule" sequence comes around
Click to expand...
I have a VF and haven't found any easy way to do a manual override that doesn't get undone by the schedule. I just modify the existing schedules to what I want -- I usually keep their time and add additional ones in between if needed so that I don't have to re-enter them. Still a pain, but less work than deleting and re-adding. However, I have IntelliTouch which probably makes it easier to have more schedules -- I think with the VS and no IntelliTouch, you've only got your 4 programs on the pump itself so that's somewhat less flexible.

If you are allowed to have overlapping schedules, then just add a new one that is almost 24 hours and so long as it's RPM is at least as high as the others, then it will override (the Intelliflo uses the highest requested RPM or GPM if there is more than one program or option that has a different RPM or GPM such as solar or gas that can come on).

As for reagent, you can even use a 5 ml sample where each drop is 1 ppm, but that has less accuracy though should get you in the ballpark.

As for the algae in pitted areas, you can try a wire brush (is that what you have been using when you say "brush"?) when the chlorine is high, but it's really about getting in those pits more than anything else. A pumice stone is more likely to remove some of your plaster surface rather than get into the pits unless you really wanted to shave off some of that plaster (probably not a good idea -- similar problems as acid washing in shortening the life of your plaster).
 
chem geek said:
twd000 said:
ok, another question

how do I set my Intellifo VS to run around-the-clock? I would like to avoid changing the set run schedule

but when I manually start Speed#2 (1500 RPM filter speed) it stops after the next "Running Schedule" sequence comes around
Click to expand...
I have a VF and haven't found any easy way to do a manual override that doesn't get undone by the schedule. I just modify the existing schedules to what I want -- I usually keep their time and add additional ones in between if needed so that I don't have to re-enter them. Still a pain, but less work than deleting and re-adding. However, I have IntelliTouch which probably makes it easier to have more schedules -- I think with the VS and no IntelliTouch, you've only got your 4 programs on the pump itself so that's somewhat less flexible.

If you are allowed to have overlapping schedules, then just add a new one that is almost 24 hours and so long as it's RPM is at least as high as the others, then it will override (the Intelliflo uses the highest requested RPM or GPM if there is more than one program or option that has a different RPM or GPM such as solar or gas that can come on).

As for reagent, you can even use a 5 ml sample where each drop is 1 ppm, but that has less accuracy though should get you in the ballpark.

As for the algae in pitted areas, you can try a wire brush (is that what you have been using when you say "brush"?) when the chlorine is high, but it's really about getting in those pits more than anything else. A pumice stone is more likely to remove some of your plaster surface rather than get into the pits unless you really wanted to shave off some of that plaster (probably not a good idea -- similar problems as acid washing in shortening the life of your plaster).
Click to expand...

this plaster is way past the point of preserving its lifespan! - looks to be circa 1977 so I don't mind scraping it a bit to get at the stubborn algae spots. MY pool brush has a mix of stainless steel and nylon bristles so I will try a full-metal one next

As far as the pump run cycle, I did what you suggested and used an "empty" Speed #7 to set a 24 hr runtime. Since it overlaps periods with the same RPM there should be no difference
 
I can't achieve shock level

I have 60-70 ppm CYA

I started Sunday night by dumping in 4 gallons of 12.5% bleach. Pool Calc indicates each gallon should add 5 ppm FC, so I figured that would get me to 20 + whatever starting FC I have. I have been running pump 24/7, brushing wall 2x a day, testing water and adding bleach 2x a day. I have tested between 15-20 ppm FC, 0 CC every time.

Just tonight I added another 2 gallons, tested at 15 ppm FC, added 2 more gallons, tested 20 ppm one hour later. I report the morning FC to provide OCLT results. By my math, it should have taken it to 25 ppm, but I only achieved 20 ppm. Is it possible to consume chlorine that fast, at night, with no algae, and no combined chlorine?

So far I have used 16 gallons of 12.5% bleach in 48 hrs and the problem does not seem to be going away. This is getting expensive. What do I do?
 

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