Can't get rid of algae

Chlorinating, maintaining the right chlorine levels,
chlorine problems. Dichlor, trichlor, cal hypo, bleach,
granules, chlorine pucks and chlorine sticks.
davethepoolguy

Can't get rid of algae

Postby davethepoolguy » Thu 02 Jun, 2011 17:14

I maintain about 15 pools a week. I have been doing this for years. Starting last year, I noticed that I was getting algae in pools even though the chlorine was high. The chemicals are all balanced properly but this is now happening in 5-6 different pools. I believe the problem to be either in the tri-chlor or the calhypo. Can anyone shed some light on what is causing it and/or how to fix it. any help would be greatly appreciated.


chem geek
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Can't get rid of algae

Postby chem geek » Fri 03 Jun, 2011 00:37

There is no mystery here. The following are chemical facts that are independent of product concentration or of pool size:

For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.
For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by at least 7 ppm.

So even with a typical 2 ppm FC per day chlorine usage, having only Trichlor as your chlorine source would result in an increase in CYA of over 2*30*0.61 = 36 ppm PER MONTH. Higher CYA levels reduce the active chlorine level requiring a proportionately higher FC level to prevent algae growth. In manually dosed pools, if you don't have the FC level be at least 7.5% of the CYA level, then algae can grow faster than chlorine can kill it. See the Pool School for more information.
davethepoolguy

Can't get rid of algae

Postby davethepoolguy » Fri 03 Jun, 2011 07:38

Makes sense. Most of the Pools I recently took over and they were using dichlor and trichlor tabs. I guessing the only way to fix it is drain the pools. I drained approx 2/3 of the water from one and changed the sand. It had no noticeable affect on the chlorine levels. I never used to have this problem. Any chance that the manufacturer's of chlorine have increased the level of cya as maybe a cost cutting measure or something. I hear I'm not the only one having this problem lately. BTW, all the pools are vinyl and located in central AL.
chem geek
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Can't get rid of algae

Postby chem geek » Fri 03 Jun, 2011 21:00

Dilution of the pool water is the only way to lower the CYA though sometimes you get lucky and it drops over the winter (which may or may not convert to ammonia creating a huge chlorine demand).

No, nothing has changed -- Trichlor and Dichlor always follow the rules I gave since they are related to the chemistry and not concentration of product. Perhaps there was less winter and summer rain overflow that in past years might have diluted the water more. Or perhaps more algae nutrients (phosphates and nitrates) have accumulated in the pools.

To prevent algae growth, you've got several choices. The most straightforward and least expensive is to use unstabilized chlorine such as chlorinating liquid or bleach and maintain the appropriate FC/CYA ratio. However, this requires adding chlorine every day or two unless you have a mostly opaque pool cover in which case you can add it perhaps twice a week. You can automatically dose by using The Liquidator or a peristaltic pump or a saltwater chlorine generator. With these techniques, you should not need any regular shocking of the pool.

If you are willing to spend more money and can only service your pools weekly, then you can have Trichlor in a floating feeder or inline chlorinator and use a weekly algaecide such as PolyQuat 60 or you can use a phosphate remover (doesn't work as well if the pool is high in organic phosphates) or add 50 ppm Borates (boric acid) to the pool. You could use a copper-based algaecide, but that can stain pool surfaces and turn blond hair greenish.
davethepoolguy

Can't get rid of algae

Postby davethepoolguy » Sat 04 Jun, 2011 06:35

thanks for the help.
paulbest
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Re: Can't get rid of algae

Postby paulbest » Wed 10 Aug, 2016 23:15

Algae spores may get into the pool through rain, wind, or contaminated equipment and swimsuits. When the swimming pool conditions are not well balanced, an algae bloom can occur overnight. These pool conditions include an improper imbalance of water chemicals, presence of nitrates and or carbon dioxide, warm temperatures and sunlight. Of course, poor circulation, filtration and sanitation are always the main cause of the algae.

How to get rid of them?

before you begin the treatment process, use a good pool brush to scrub off the algae from the floor and the sides of your pool to break it up so that the chemicals can work faster. If your pool is made of concrete, use a steel brush but if it is a vinyl pool, a nylon swimming pool brush is recommended.

1.Maintain adequate basic chemical levels (chlorine/bromine or PHMB or copper).
2.Never use a chemical product you don't really need.
3.Purchase and USE a test kit for the sanitizer/oxidizer/algaecide you are using.
4.Shock appropriately, in the evening, not in the morning.
5.Run your pump at least 6 hours per day in TWO different periods.
6.Brush the ENTIRE pool at least once every two weeks during the swim season.
7.Do NOT use the cheap foamy algaecides.
8.Keep your pH between 7 and 8.
9.If available, use borax, not baking soda or soda ash, to raise your pH as needed.
Denniswiseman
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My Pool: 10k inground fibreglass, Telescopic Cover, Hayward Powerline pump, Quality filter with glass media, 27kw output heat pump, K-2006C test kit
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Re: Can't get rid of algae

Postby Denniswiseman » Thu 11 Aug, 2016 12:32

The best way to get rid of algae is to slam your pool http://www.troublefreepool.com/content/125-slam-shock-level-and-maintain-shockingl
Follow the instructions exactly
Mitchouu22
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Re: Can't get rid of algae

Postby Mitchouu22 » Mon 05 Sep, 2016 15:03

chem geek wrote:There is no mystery here. The following are chemical facts that are independent of product concentration or of pool size:

For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.
For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by at least 7 ppm.
paris taxi Airport
So even with a typical 2 ppm FC per day chlorine usage, having only Trichlor as your chlorine source would result in an increase in CYA of over 2*30*0.61 = 36 ppm PER MONTH. Higher CYA levels reduce the active chlorine level requiring a proportionately higher FC level to prevent algae growth. In manually dosed pools, if you don't have the FC level be at least 7.5% of the CYA level, then algae can grow faster than chlorine can kill it. See the Pool School for more information.

Hey, thank you for these informations and for the link :)
Mrsdan1983
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My Pool: I have a L shaped pool, 40 x 20 on the long sides. I also have a hot tub that overflows into the shallow end of the pool. I have a sand filter, and it is a salt pool. I have a variable speed Hayward pump.

Re: Can't get rid of algae

Postby Mrsdan1983 » Mon 12 Sep, 2016 17:24

When checking my pool chemicals at the pool store, my water is clear and balanced, but I have brown silt on the bottom. I have used drop-out and then manually vacuumed out my pool. The problem is it keeps coming back. I have a salt water pool, and I'm very frustrated at not being able to keep it clean this year.
Denniswiseman
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Posts: 283
Joined: Tue 06 Sep, 2011 05:48
My Pool: 10k inground fibreglass, Telescopic Cover, Hayward Powerline pump, Quality filter with glass media, 27kw output heat pump, K-2006C test kit
Location: United Kingdom

Re: Can't get rid of algae

Postby Denniswiseman » Tue 13 Sep, 2016 02:15

The best way to get rid of algae is to Slam
Follow the instructions and do exactly as they say
And don't use the pool store testing as they are not that accurate and you will need to test a lot

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