total and free chlorine

Algae problems in swimming pool water.
Green (cloudy) water or slimy pool walls.
Black algae. Mustard algae. Pink or white pool mold.
pup55

total and free chlorine

Postby pup55 » Sun 23 Aug, 2009 11:24

I keep having problems with algae growth and would like to know if the total and free chlorine are to high could this be a cause? My total and fre are both at 10 and I cannot seem to get it lower.I have an off line feeder and I keep adjusting it and they both stay at 10. Could this be the cause of the algae growth?


chem geek
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Location: San Rafael, California

total and free chlorine

Postby chem geek » Sun 23 Aug, 2009 16:44

Read the Pool School and get yourself a good test kit -- either the Taylor K-2006 you can get at a good online price here or the TF100 kit from tftestkits.net here with the latter kit having 36% more volume of reagents so is less expensive per test. Since you have an a chlorine feeder that probably uses Trichlor pucks/tabs, your Cyanuric Acid (CYA) level may be very high and that makes chlorine less effective allowing algae to grow faster than chlorine can kill it. See Defeating Algae in the link I gave to the Pool School.
pup55

total and free chlorine

Postby pup55 » Mon 24 Aug, 2009 16:45

Thanks for your response. My cyanuric acid is at 30-50 right now.
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

total and free chlorine

Postby chem geek » Tue 25 Aug, 2009 01:18

Shock the pool with 20 ppm FC. How sure are you that the CYA is 30-50 ppm? Test strips and pool store results are notoriously inaccurate for CYA. If you use Trichlor pucks in an offline feeder (what does that mean "offline" -- usually it's referred to as an inline chlorinator), then unless you've got a small pool with a short season and a sand filter backwashed weekly or have lots of rain overflow, then the CYA is likely higher. For every 10 ppm FC added by Trichlor, it also increases CYA by 6 ppm. Even with a low daily FC usage of 1 ppm, the CYA added by Trichlor would be over 100 ppm in 6 months if there were no water dilution.
pup55

total and free chlorine

Postby pup55 » Tue 25 Aug, 2009 19:54

I am using test strips with a sand filter and I do backwash weekly with 28,000 gallons. I am going to purchase a new test kit and recheck the cya.
pup55

total and free chlorine

Postby pup55 » Wed 26 Aug, 2009 16:35

Update, came home from work and pool has algae growing again.
TH 100
TC 10
FC 10
PH 6.2
TA 80/120
CA below 0

I just scrubed the pool to get rid of all the Algae and will shock it tonight. I have had the pool for 9 years and haven't changed anything it the algae keeps coming back. I also have another issue. You can smell the chlorine in the pool and anytime I add any type of powdered chemical the pool turns cloudy right away and will not clean up for a good week.HELP!!!!!!!!!!!!!! I am using 2 different types of test strips and I am going out to by a test kit this week.
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

total and free chlorine

Postby chem geek » Thu 27 Aug, 2009 00:47

Two days ago you said your CYA was 30-50 and now you say it's "below 0" (it can only get to zero, not below). With a proper test kit, you'll be able to know what is really going on.

If you are adding Cal-Hypo and it remains cloudy, then your Calcium Hardness (CH) may be high. If you use chlorinating liquid or 6% unscented bleach, then this won't add either CYA nor CH. Please read Defeating Algae in the Pool School link I sent to you. The key is to maintain a sustained high level of chlorine in the pool to kill algae and then after it is killed and the water is clear then maintaining a proper FC/CYA level will keep the algae away.
pup55

total and free chlorine

Postby pup55 » Thu 27 Aug, 2009 16:50

I am having a really tough time matching the colors up on the test strip. When I get the new test kit it should be better. Thanks for your help, it sounds like i am starting to bother you. again thanks for your help.
czechmate
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Posts: 401
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My Pool: 16 x 32 gunite21000 gal., Diamond Brite Blue, Swimquip XL pump, DE36
Location: Texas

Total and free chlorine

Postby czechmate » Thu 27 Aug, 2009 17:40

Look at the number of Chemgeek postings.
If he ever felt bothered he would have stopped after 1000 replies.
I think that 5 drops on a liquid are much better ways of testing and more economical than strips.
Keep them inside the house though to retain the proper results.
Me...
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Posts: 302
Joined: Thu 26 Feb, 2009 11:11

Total and free chlorine

Postby Me... » Fri 28 Aug, 2009 10:42

I am starting to really like these, the Pro 7 kit in particular. Saves deciphering colors.

http://www.lamotte.com/pool_spa_water/p ... _kits.html

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